Dunes in a Transitional Zone: Using Dune Horizonation, Stratigraphy, and Elemental

Leaching to Determine the Relative Ages of Green Point Dune Complex and Elberta Dune

Complex

Emma Fulop

Dr. Brad Johnson and Dr. Dave Martin

Capstone Project

ENV 499

Spring 2015

______________________________________________________________________________

Abstract

Soil development and stratigraphy can provide valuable insight into the stabilization and

activation history of dune complexes along the northeaster shoreline of Lake Michigan. The

Green Point Dune Complex (GPDC) and Elberta Dune Complex (EDC), found near Frankfort

Michigan, lie at a latitudinal transition point between perched dunes to the north and coastal

lake-plain dunes to the south. Examining dunes at this transition point allows for comparison

between the two dune types. GPDC consists of seven separate parabolic lake-plain dunes while

EDC, approximately 6 km north, comprises five parabolic dunes perched on a glacial bluff.  Both

sites are characterized by stabilized dunes with overlapping arms which indicate non-concurrent

periods of migration. Here, we attempt to determine the relative ages of these two dune

complexes through stratigraphic relationships, field mapping, and soil development (including

horizonation, pH, clay content, and Fe activity ratios). Soil profiles (typically A/E/B/

horizonation) at the dune crests reveal slight variances that can be used, along with dune arm

stratigraphic relationships, to determine relative ages between dunes. Dunes at GPDC have seven

unique ages relative to each other, with slight disagreements between field and lab ages.

Calibrated ages, as compared with Lichter’s (1998) regional dune chronosequence, show that all

of the dunes in the complex formed within the last 2500 years. We compare elemental leaching

in the complexes with Lichter’s chemical depletion to determine more specific calibrated ages;

both complexes exist within an age range of 300-2000 years. EDC stabilized later than GPDC

and both complexes stabilized non-concurrently. Geochemistry has great potential to accurately

determine the stabilization dates of dunes.

Additionally, we looked at dune-axis orientation, which ranges from west to southwest

and shows differences in environmental conditions (i.e., wind direction) during formation at

GPDC. Dunes at EDC are all oriented in a southwestern direction, have four distinguishable

migration periods, and are interpreted to be younger than GPDC based on soil horizonation. Our

future work in the area will focus on optically stimulated luminescence (OSL) dating of the

dunes with the goal of further constraining the timing of dune migration. This improved

chronology will help us to understand the causes of dune stabilization and activation by

comparing nearly adjacent perched and coastal lake-plain dunes and allow us to understand what

techniques result in optimal dune ages.

Introduction and Literature Review

Overview

Studying the coastal processes that formed the dunes along Lake Michigan can help

inform understanding of the paleoclimate and the causes of dune activation and stabilization.

This information improves knowledge about both past and contemporary processes. This study

uses the stratigraphy1 and soil horizonation of two adjacent dune complexes to determine the

1 For this study, the physical layering or overlap of dunes or parts of dunes.

relative dates of the dunes in comparison to each other, connecting this regional study to the

more general geomorphic history of the area.

Previous studies that use dune complexes to understand stratigraphy and paleoclimatic

influences in the past only focused on one type of complex at a time. Additionally, much

research has been done on coastal foredunes (Lichter 1995; Olson 1958) but scientists have only

recently begun to study large parabolic dunes similar to the ones in this study (Arbogast and

Loope 1999; Arbogast et al. 2002; Lepcyzk and Arbogast 2005; Loope and Arbogast 2000).

Therefore this study differs from previous studies because it focuses on Green Point Dune

Complex (GPDC) and Elberta Dune Complex (EDC), which lie at a transition point between

southern lake plain dunes and northern perched dunes. A side-by-side comparison between these

two dune types has not yet been done, and it may help to distinguish between similarities and

differences in the formation history of the two dune types.

It is important to review the existing literature and scientific studies to place this study

within a larger context. There are incongruities surrounding understandings of the paleoclimate

and dune processes that my study could help sort out. Conversely, the literature could justify

these findings by allowing for comparison of my data with accepted models. Ultimately, this

regional study can add to the more general story of dune formation and movement along Lake

Michigan.

Regional Geology

The coastal dunes along the eastern shore of Lake Michigan have been separated into two

different types: perched dunes and lake-plain (or lake terrace) dunes (Arbogast et al. 2002). Both

types are parabolic, large (often taller than 30 meters), and commonly exist in complexes

containing numerous individual dunes (Arbogast and Loope 1999; Lepcyzk and Arbogast 2005).

Perched dunes exist on highland bluffs while lake-plain dunes lie at lake level. They are also

distinguished geographically: Manistee, Michigan is commonly used as the geographic

separation point with perched dunes to the north and lake-plain dunes to the south (Arbogast et

al. 2002; Lepcyzk and Arbogast 2005). There may also be differences in the timing of formation

that are not fully understood: Loope and Arbogast (2000) found that the northeast lakeshore

stabilized less than 1500 BP cal years ago while Arbogast et al. (2002) found that the southeast

shore formed 2500 BP cal years ago, showing that time as well as geography may separate these

dune types. GPDC and EDC exist adjacent to each other and this transition point may help

understand these proposed similarities and differences.

Morphology

Dune Formation

Researchers believe that parabolic dunes develop from blowouts during several periods

of eolian activity because of wind energy and sand transportation (Lepczyk and Arbogast 2005;

Gares and Nordstrom 1995; Hansen et al. 2008). The Green Mountain Beach dune near Holland,

Michigan provides current evidence for this transition because it is currently developing into a

parabolic dune from a blowout (Hansen et al. 2006). Studying the migration of this dune can

provide information about how sand and wind energy work together to form parabolic dunes and

provide information about the weather and climate at the time of formation (Gares and

Nordstrom 1995; Hansen et al. 2009; Hansen et al. 2006). Since parabolic dunes develop from

sand transportation, they are indicative of high energy environments with enough wind energy to

move sand but wind is not the only climactic factor involved (Gares and Nordstrom 1995;

Lepczyk and Arbogast 2005).

Dune Orientation

Map and field evidence show that within GPDC, the dunes have varying orientations,

which could be indicative of varying environmental conditions. Dune type and crest orientation

may provide insight into the dominant wind patterns and weather regimes of the past, allowing

for relative dating (Kocurek and Ewing 2005). A study of a lake-plain dune complex in

Holland, Michigan, comparable to GPDC, reveals that all of the dunes lie with the arms facing

west while aerial images of GPDC reveal a range of dune-axis orientation from northwest to

southwest (Hansen et al. 2010). This may point to a differences in environmental conditions (i.e.,

wind direction) during formation that should be explored further.

Interference

Another factor that affects dune stabilization and activation is human interference

through activities such as overgrazing, clear-cutting, or vehicular disturbance (Yizhaq et al.

2007). This disruption does not factor into the initial creation and stabilization of dunes but it

does complicate the current dune record by altering the soil profile and dune structure.

Geomorphic History

Dune building began after deglaciation occurred during the Holocene, at approximately

11,600 cal. years BP. This deglaciation formed the Great Lake Basin, which includes modern

day Lake Michigan (Loope et al. 2004). The Holocene is marked by variations in the lake level

through climate fluctuations that impacted dune building, focusing especially on the Nipissing

Transgression2 (Loope et al. 2004). It is widely agreed that modern dune building across the

entire western coast of Michigan began during the Nipissing Transgression, but there are many

differing ideas about the specifics within this period (Arbogast et al. 2002; Hansen et al. 2010;

Loope et al. 2004) See Figure 1 in the Appendix for a figure of lake level fluctuation.

2 A period of high lake levels within the Great Lakes (Arbogast and Loope 1999).

There are disagreements regarding the exact dates of dune field formation within the

Holocene but most studies agree on the general timing. Early studies determined that the

deposition of eolian sands began during the Nipissing Transgression between 6000-4000 BP cal

years (Anderton and Loope 1995; Arbogast and Loope 1999; Mason et al. 1997). More in-depth

studies found that, while dune building may have begun during this period, it did not end then

and even continues into the present day (Lepczyk and Arbogast 2004). Hansen et al. found that

early dune building occurred between 5000-3500 BP cal years after a peak in lake levels,

stabilized, and then reactivated from 1100-present (2006). This timing agreed Arbogast et al.,

who stated that 75-80% of dune building occurred between 4000-2500 BP (2002). Loope and

Arbogast, however, found that the majority of deposition occurred within the last 1500 BP cal

years (2000). Thus, the more recent studies agree that, while original dune activity began during

the Nipissing Transgression, growth and migration has occurred sporadically into present day.

Lake Levels

Along with the disparities among dating the periods of activation and stabilization, there

is disagreement about the corresponding climate and lake levels. One of the first studies based

solely on Michigan dunes focused on beach ridge dunes and found that fluctuations of lake level

were most responsible for dune morphology (Olson 1958). Olson specifically found that dunes

formed as underwater ridges were exposed due to falling lake levels over 30 year periods. The

model he developed is still accepted as an explanation of coastal activity in the recent past but

does not explain older dune formations or the creation of large parabolic dunes. By adding

absolute dating techniques to the relative techniques Olsen used, later studies found evidence

against low lake levels causing the building of large parabolic dunes (Arbogast et al. 2002;

Arbogast and Loope 1999; Loope and Arbogast 2000). These authors realized that smaller dune

ridges formed during the low lake levels would have been destroyed by fluctuations to higher

levels, creating the model of episodic construction. Recent studies have expanded on this

episodic construction to connect periods of dune building with high lake levels and periods of

stabilization with low lake levels for both perched dunes and lake plain dunes (Anderton and

Loope 1995, Lepczyk and Arbogast 2004; Loope et al. 2004, Loope and Arbogast 2000).

Researchers now accept that high lake levels destabilize bluffs through erosion and low

lake levels reduce the supply of sediment by stabilizing the bluffs (Lepczyk and Arbogast 2004).

High lake levels also bring sediment to shore, increasing the supply for lake-level dunes (Lovis

et. al. 2012). However, low lake levels also expose more sediment. There are slight

disagreements about the timing of these periods and what other climactic processes play a role in

dune formation.

There is a connection between lake level change and sediment deposition but the

relationship is not fully understood because there are many other factors at play (Barnhardt et al.

2004). For example, isostatic rebound3 contributes to periods of lower lake levels, especially in

northern Michigan (Barnhardt et al. 2002; Fisher et al. 2007). Climate change during the

Holocene also affected wind energy and direction, wave energy, sediment deposition, and plant

succession (Fisher and Loope 2005), complicating the climate record. Since a single study

cannot correctly recreate the paleoclimate and geomorphic movements of the entire eastern Lake

Michigan coast, it is important for more regional studies to add information and tease out trends

in the climate data.

Bistability

Both dune complexes contain active and stabilized dunes. This bistability, seen in many

dune complexes, reveals a complicated dynamic among development driving forces (Yizhaq et

3 The uplift in earth’s crust that occurs as the weight of ice is removed by melting (Lovis et al. 2012).

al. 2007). The conditions that allow for active and stabilized dunes to coexist in the same

complex is not yet fully understood, but Yizhaq et al. believe that wind energy plays an

important role (2007). Vegetation reduces the impact of wind on a dune and allows for

stabilization, but a change in climate, such as increased temperatures and aridity, can disrupt

vegetation and reactive a dune (Arbogast et al. 2002; Hugenholtz and Wolfe 2005; Yizhaq et al.

2007) These authors propose that a drastic change is necessary to activate a stabilized dune and

so an intermediate energy level may allow for bistability.

Relative Dating Methods

The differences in the dates of stabilization and activation could be due to errors in dating

techniques discussed below. A combination of these techniques would create a more complete

climate record and allow for a more accurate interpretation of results.

Stratigraphy

Stratigraphy looks at both rock layers, the ordering of strata, and the layering of geologic

forms as indicators of age. Generally, the deepest layers are considered to be the oldest, unless

there is evidence of uplift or reordering within the profile. In this study, the overlap of dune

forms are the geologic forms that we observed. We interpret the top dune arm or ridge to be

younger than the bottom arm.

Soil Horizonation

Many of the studies rely on soil cores to create chronosequences and understand dune

growth within the greater context of the paleoclimate. Studying podsolization4 can provide

information about the weathering and age of a particular site and can allow for comparison

among dunes (Arbogast and Loope 1999). For example, the podsolization of areas with known

4 Podsolization is the process of elements, minerals, and organic matter moving downward through a soil profile (Binestock 1999).

ages can be used to relatively date dunes with similar stratigraphy (Arbogast et al. 1997). The

thickness and color of soil horizons5 can provide information about the amount of weathering

that a particular dune has undergone (Arbogast et al. 2002).

Individual materials within the soil, in particular clay minerals and iron oxides, can also

reflect weathering and the paleoenvironment (Birkeland 1999). Lichter created detailed

chronosequences of over 100 dune ridges in northern Michigan. He focused on organic matter

accumulation, soil dilation, and element translocation to determine temporal patterns over the

last 400 years (Lichter 1998). He found that the downward transportation of Fe and Al through

mineral weathering are a function of time, along with an increasing thickness of the elluvial

zone. Ca and Mg are rapidly depleted from the upper horizon and their relative absence in a

chronosequence can occur within a few hundred years (Lichter 1998). Additionally, Lichter

found that each element interacts differently within the soil profile, creating a unique leaching

trend (1998). Looking at concentrations of these elements within the soil can provide a clearer

time since dune stabilization.

Field Notes and Aerial Photographs

Studies that look at the development of modern sand dunes make use of aerial photos

(Hugenholtz and Wolfe 2005; Olson 1958). A study of active sand dunes on the Canadian prairie

compared photographs with climate data over the past 75 years (Hugenholtz and Wolfe 2005).

These authors were able to extrapolate these data to more historic dune activity by creating a

trend between wind speed and active land area. Through this, they found that modern dunes may

still be recovering from a disturbance in the 1700s (Hugenholtz and Wolfe 2005). Additionally,

5 Horizons are the layers that develop in a soil profile. Each horizon has individual properties due to vertical weathering (Binestock 1999).

aerial photographs can be useful in understanding the general morphology and trends of a study

site by showing relationships that cannot be determined from the ground.

Absolute Dating Methods

Radiocarbon Dating

Many of the large parabolic dunes in Michigan contain radiocarbon samples because they

were forested or covered in vegetation during periods of stability, and then these layers were

buried when the dunes reactivated (Arbogast et al. 2004). Radiocarbon dates are seen in charcoal

pieces and/or soil layers, called paleosols. The buried soil and vegetation can often be

radiocarbon dated to determine a specific period of stability (Arbogast et al. 2004; Arbogast and

Packman 2004). However, radiocarbon dates are not always correct; samples of charcoal can be

washed or blown into dunes, creating false ages (Arbogast and Packman 2004; Hansen et al.

2010). They also do not always exist in a study site and, when they do, can only provide

information about the last major period of stabilization and leave out finer data points. More

refined dating methods are often used in conjunction with radiocarbon dating, especially when

buried soils do not exist in the study site (Arbogast et al. 2002; Mason et al. 2004).

Optically Stimulated Luminescence

Optically stimulated luminescence (OSL) provides an absolute age for the last time sand

grains were exposed to the sun, or the latest instant of transport (Arbogast and Packman 2004;

Arbogast 2000; Hansen et al. 2002; Mason et al. 2004). These method can be used independently

or in conjunction with other methods to get a better understanding of the geomorphic past of the

site.

Example Study

The study of the Nodaway perched dune field along Lake Superior in Upper Michigan

used both relative and absolute testing methods to determine the approximate time since

stabilization. The study looked at the sand in dune crests because crests are the primary zone for

deposition (Arbogast 2000). The researchers analyzed the samples for color, horizonation, and

overall podsolization to quantify the relative ages of each individual dune focusing on the

leaching of Al and Fe compounds (Arbogast 2000). Radiocarbon and OSL samples were also

taken from each pit to determine the absolute ages. The authors determined that, while there

were small differences seen in soil development that could mean variations in timing of

stabilization, they are most likely due to differences in vegetation and microclimate. The

absolute dates correlate with high lake stands during the Nipissing Transgression but minor

differences in the soil showed that there were slight local differences among dunes in the

complex. The authors ultimately concluded that the Nodaway dune fields follows the Anderton

and Loope perched dune model (1995) but local factors affect stabilization (Arbogast 2000). The

relative dating methods in this study allowed the authors to understand the smaller influences of

stabilization while the absolute ages provided specific dates consistent with the relative data.

Methodology

Study Sites

GPDC and EDC exist adjacent to each other and this transition point may help

understand these proposed similarities and differences. Specifically, GPDC and EDC lie along

the central eastern shore of Lake Michigan in Michigan. GPDC lies south of Frankfort and just

north of Lower Herring Lake while EDC lies in the town of Elberta, located just south of Betsie

Lake (Figures 1 and 2). Elberta lies approximately 6 km north of GPDC.

Figure 1. The location of GPDC in relation Figure 2. The location of Elberta dune complex to Lower Herring Lake (Google Maps 2015). next to the town of Frankfort and Betsie Lake (Google Maps 2015).

The dunes in both of these complexes are large parabolic dunes. Letters were used to

identify the dunes; the letters correspond to the order in which each dune was studied but do not

relate to age. GPDC is a lake-plain complex made up of seven dunes; the lake level is

approximately 150 meters above sea level. Six of these dunes are stabilized and forested while

one of them is active. A foredune sits between the active dune and the lakeshore, helping to

funnel the sand and create the parabolic shape. The eastern portion of GPDC lies on beach sand

while the western portion lies on a glacial moraine. Elberta consists of five perched dunes; the

glacial bluff that these dunes exist on reaches 200 meters above sea level. Two dunes are

completely stabilized while three exhibit signs of activation and/or human disruption; these signs

include blowouts and ATV tracks. The most obvious example of human activity is that an

abandoned water tower sits at the crest of Dune 3 and a road leads from this water tower down

the leeward side of the dune.

Field

I went to the field with my mentor Brad Johnson and field assistant Kelsey Krueger to

gather data. We focused on recording as much information about the two complexes as possible,

both qualitative and quantitative. This task involved extensive note taking and the collection of

soil samples, both for analysis of soil profiles and OSL dating.

We explored the study sites and mapped the morphology of both dune complexes,

identifying areas of overlapping dune arms, incised channels, eroded areas, and areas of modern

eolian activity. We used a GPS to mark these points, as well as to mark each soil pit that we dug.

Two pits, measuring 1m x 1m x 60cm, were dug on the crest of each undisturbed dune

and soil samples were collected from the crest of each stabilized dune. The topsoil was removed

intact and samples were not collected from this horizon. Samples were taken from each

underlying horizon and soil profiles were described, including depth of horizons, color, and

texture, using Birkeland (1999) and the Soil Survey Handbook (Soil Survey Division Staff 1993)

as guides. See Figure 2 in the Appendix for a figure explaining the main horizons in a soil

profile.

We collected one OSL sample from the crest of each dune. The samples were collected

from the B horizon6 and the pit was chosen based on ease of sampling. We collected OSL

samples under a black tarp with black PVC piping and foam core to prevent exposure to sunlight,

which would ruin the samples. Theses samples hopefully will be analyzed at a later date to

determine the absolute age.

6 The zone of accumulation (Binestock 1999).

Lab

The lab tests focused on common soil characteristics to uncover possible trends in each

complex independently as well as across both complexes using the soil samples and notes

collected in the field. Soils were air dried and sieved to 2mm. The dry color was recorded before

any other tests were performed in the lab. We also created maps in ArcGIS using field data and

aerial imagery after the field work was complete.

Clay

We measured the amount of clay in 20 g samples from each B horizon soil sample. Using

a 63 micron sieve and distilled water, we separated the clay particles from the rest of the sand

and into Erlenmeyer flasks. These flasks were placed in an oven and baked until all of the water

had evaporated. We then measured the weight of each flask, subtracting the original weight to

determine the weight of the clay alone.

pH

The pH was determined for all soil samples collected. We used 0.01 M CaCl2 to create

the solution and allowed each sample to settle for at least 30 minutes before measuring the pH of

the solution with a handheld pH meter.

Iron Ratios

We analyzed the extractable iron ratio of the B horizon for GPDC and the E horizons7 of

EDC following a method based on the work of McFadden (1985), McKeague and Day (1966),

and Mehra and Jackson (1960). Measuring the iron activity ratio is a two part process as we had

to measure both iron oxalate (Feo) and iron dithionite-citrate (Fed).

The iron activity ratio, of Feo to Fed, provides a measure of oxidation with numbers closer

to zero being more oxidized. We demagnetized all of the Feo samples by using a magnet to

7 Zone of leaching (Binestock 1999).

remove the magnetite from the samples. Fed samples were not demagnetized. We then measured

out 0.5 g of the soil samples (that had previously been ground to 150mm) from each dune pit and

added the determined amounts of extracting solution. The citrate-dithionate method was used for

Fed while the ammonium oxalate method was used for Feo. The Fed samples were put in a water

bath while the Feo samples were shaken for maximum extraction. All samples were centrifuged

and decanted. We ran these solutions through Davidson College’s Atomic Absorption

Spectrometer (AAS), which determines the quantity of a particular element in a solution by

measuring the light output of a flame in the machine. Once we had the mg/ml of each solution

measured, we entered these numbers into equations specific for Feo and Fed to create the iron

activity ratio.

Element Concentrations

We digested sand samples following the EPA 3050B: Acid Digestion of Sediments,

Sludge, and Soils method (EPA 1996) and analyzed the solutions using inductively coupled

plasma atomic emission spectrometry (ICP-AES). The results from this method will be

compared to the elemental concentrations determined in Lichter (1998).

Sand samples were taken from each pit selected for future OSL dating to allow for future

comparison between dating methods. A ratio of sand from the A and E horizons were mixed

from each dune pit to mimic the top 15 cm of soil, which was the depth that Lichter sampled to

in his study (1998). The dune pits used in this method are GA, Pit 1 GB, Pit 2 GC, Pit 1 GD, Pit 2

GE, Pit 1 GF1, Pit 3 GF2, Pit 1 GG, Pit 2 ED, and Pit 1 EE. Additionally, a reagent blank and a

method blank were created8.

8 A reagent blank goes through the entire procedure but does not have any sample in the vessel. A method blank is a vessel that contains the reagents from the procedure but is not heated or refluxed.

One gram of each of the sand samples was placed in a 100 ml scintillation vial and 10 ml

of a 1:1 solution of HNO3 and deionized water was added. The vials were heated for 10 minutes

at approximately 95°C. Once the samples cooled, 5 ml of concentrated HNO3 was added and the

solutions were heated for 30 minutes. This step was repeated a second time or until the gas being

evaporated from the solution was no longer colored. The vials were then heated without boiling

for two hours. Once they cooled, 3 ml of H2O2 and 2 ml of deionized water were added to each

vial. H2O2 was then added in 1 ml increments until the samples stopped effervescing; overall, an

additional 9 ml of H2O2 were added. The vials were then heated until they had evaporated to

approximately 5 ml. At this point, 10 ml of concentrated HCL were added to each vial and the

samples were heated at 95°C for 15 minutes. After the samples cooled completely, the remaining

sand was filtered out and the solutions were diluted with water to 100 ml.

These samples were then sent to the Center for Applied Isotope Studies’ Chemical

Analysis Lab at the University of Georgia to be analyzed using ICP-AES and the concentrations

of 20 elements was sent back, reported in ppm. The data was calibrated by subtracting the

method blank concentration from the dune concentrations. Data that did not reach the specific

detection limit for each element was marked and not considered in the analysis. See Table 1 in

the Appendix for the raw data.

Future Tests

We hope to send OSL samples to a lab in order to learn the absolute ages of each dune in

both complexes.

Results and Discussion

Overview

The qualitative field results were used to determine preliminary relationships among the

dunes in each complex. The quantitative lab results either supported these results or provided

different interpretations of dune movement and stabilization. The field and lab results work

together to form a more complete picture of the region than one type of data alone could provide.

Field Results

The preliminary relative ages of seven dunes were identified within GPDC and of five

dunes within EDC were made using stratigraphic field observations (Figures 3 and 4). We also

noted important morphological features and relied heavily on dune overlap to determine age

relationships within the complexes.

Figure 3: The relative ages of Green Point Dune Complex as found in the field.

Figure 4: The relative ages of EDC as found in the field.

Green Point Dune Complex

The active dune (GA) lies along the beach in the center of the complex. The height and

position of the dune crest were not measured but GA appears smaller than all of the other dunes

in the complex and it is oriented at approximately 85°9. The active dune is set behind a foredune

around which the sand supply from the beach is funneled. It is surrounded by wooded dunes on

the other three sides. The dune has a secondary ridge rising from the primary sides. Long beach

grass grows on the sides of GA while both the leeward and windward sides are void of

vegetation. The tree line begins at the crest of the secondary ridge, growing away from the active

dune. The leeward side of the dune does not appear to be at the angle of repose and is less steep

than the windward side.

Dune B (GB) is the northern most dune in the complex; the crest lies at 44.580830°N/

86.219805° W and has an altitude of 230 m. The dune is situated at approximately 40°. The arms

of this dune are very steep as they lead up to the crest and are not long when compared to the

other dunes in the complex. The southern arm of GB ends at the secondary ridge of GA. The

northern arm ends within the forested area of the beach and does not reach the active sand.

Dune C (GC) is positioned directly behind GA and shares the 85° orientation; the crest lies

at an altitude of 240 meters and is located at 4.578349° N/ 86.215214° W. The windward side of

the dune is hummocked by intermittent drainage ditches and dry stream channels. The ridges

made by these features are not large enough to be seen on a USGS topographic map. The

southern arm is fairly steep and sandy. The vegetation consists of shrubs, moss, and small trees.

Tree cover increases as you advance towards the crest. The northern arm of GC intersects

perpendicularly with GB; GC is presumed to be older than GB because it lies below the arm of GB.

9 Degrees of orientation is determined by a compass rose. Due East is 90°, South is 180°, etc.

An arm of GD also intersects and lies on top of the southern arm of GC but this relationship is not

as obvious as the former.

The leeward side of Dune D (GD) begins a few meters in from a residential road that leads

to houses built along the shores of both the Lower Herring Lake and Lake Michigan. The

southern arm is very long and gradually leads up to the crest, but the immediate leeward edge of

GD is fairly steep. The crest has an altitude of 210 m and at 44.576313°N/ 86.217571°W. It is

situated at approximately 120°. The windward side is not steep and appears to have a drainage

ditch flowing through the middle. The dune is covered in pine trees and dead brush. There are

very few deciduous trees. The northern arm of GD lies on top of GB and the end of the arm is

covered by GA, and so the relative age of GD is younger than GB.

The leeward side of Dune E (GE) ends on a glacial moraine. It is heavily wooded with

pine and birch trees, among others. The crest lies at 44.584478°N/ 86.219839°W and has an

altitude of 270 meters, oriented at approximately 30°. While there is no evidence of fluvial

channels on the immediate windward side, the eastern arm is deeply incised. The eastern arm of

GE is eventually truncated by GF, meaning that GE is older.

Dune F (GF) lies at the same 30° orientation as GE, has an altitude of 272.2 m, and is

located at 44.584465°N/ 86.213403°W. The western arm of GF cuts on top of GE. This arm of GF

is taller than the arm of GE. The crest of GF is split into two lobes (GF1 and GF2) but is identified

as a single parabolic dune. The 1 lobe is slightly taller and less wide than the 2 lobe. The

windward side of GF is very shallow and does not show any evidence of the two lobes, so any

information about their origin has been worn away. The windward side does contain much

evidence of drainage channels and erosion. There are many seedlings and bushes on the crest,

with pines on the leeward side.

Dune G (GG) has an altitude of 233 m, is located at 44.58797°N/ 86.21242°W, and

oriented in an approximately 40° direction. Its northern arm lies beneath the southern arm of GF

but this is a very subtle relationship because GG’s northern arm only gradually rises in elevation.

The southern arm of GD is very long and runs into the back of GC. GG is covered in old vegetative

debris and pine as well as deciduous trees. It is very brambly and it was difficult to walk along

the arms of the dune. It appears as though the GG southern arm was incorporated into the

formation of GC or acted as an obstacle and manipulated the formation of GC.

Through these observations, the preliminary relative ages of GPDC are as follows, from

youngest to oldest: GA, GB, GD, GC, GF1, GF2, GE, GG (Figure 3). Relative ages are depicted by

color, with red representing the youngest dune and dark green representing the oldest dune. The

ages between GB and GD and between GE and GG are not as certain as the other ages because

these dunes do not ever interact with each other. Since age could not be determined by overlap, it

was inferred through other observations, such as height and stratigraphy.

Age Discrepancies in GPDC

Many dunes appear similar in age in the field because morphology changes little in the

small time frame in question and the stratigraphic relationships are not entirely clear. We

interpreted GG to be older than GE because it seems to be more weathered as it contains many

more hills and hummocks. The vegetation cover is also thicker on GG. GD was inferred to be

older than GB because the horizonation of GD appeared to be more advanced with a possible B2

horizon. GD also had more hummocks and stream channels than GB, giving it the appearance of

being more weathered. Ariel photographs verify these observations.

There was strong stratigraphic evidence to suggest that GC is older than GB and GD. The

latter two dunes both lie on top of GC’s arm and they are smaller dunes overall, meaning that

they began formation after GC. However, we began to question this relationship when comparing

the surface appearance of GC to GB and GD. The latter dunes are heavily wooded and have thick

topsoil while the leeward slop of GC is sandy and only lightly vegetated near the top of the arms.

On first glance, the soil profile of Gc also appeared less developed; the horizons were not as thick

as in the other dunes and the transitions were not as clear. This information led us to believe that

GC may have experienced a local disturbance and briefly reactivated.

Elberta

The Elberta Dune A (EA) may simply be a blowout instead of a parabolic dune; the dune

is oriented at approximately 45°. The leeward side is extremely steep and heavily forested. The

windward side is very steep and looks like a bowl shaped basin of sand with a small foredune at

the foot of the basin. There are paths for humans and off-road vehicles across the entire dune.

The leeward side of EA backs up against EB.

Elberta Dune B (EB) has a non-vegetated windward center leading to the crest that shows

evidence of human paths and off-road vehicle tracks. The southern arm is truncated by EA and

the northern arm ends at the bluff edge without touching the adjacent dune, Ec. The crest of the

dune is positioned at approximately 30°. EB forms downhill, meaning that the crest is lower in

elevation than the base of the dune. This is because it flows from the perched bluff down to lake

level, ending on a glacial moraine.

The windward side of Elberta Dune C (Ec) is expansive and contains various hills and

valleys leading down to the bluff. Ec also loses elevation as you move away from the lake and the

crest lies at 30°. Its southern arm does not touch EB but part of the northern arm is covered by a

lobe of ED’s southern arm. There is a road leading up the leeward side of Ec; the dune lies against

the town of Elberta and an old water tower exists at the top of the dune.

Elberta Dune D (ED) has a very long southern arm that begins on top of Ec. There are

walking trails and evidence of anthropogenic alteration in the windward basin of ED but the

amount of interference is much less than seen on EA, EB, and Ec. The crest of ED is covered in

small plants but there are large trees growing along the arms and on the leeward side. The crest is

at an altitude of 245 m and is found at 44.623541°N/86.232118°W with an orientation of 30°.

There is an incision channel leading down the windward side from the crest. The northern arm of

ED is covered by the southern arm of EE. This dune does not slope back as much as the other

dunes in the complex.

Elberta Dune E (EE) is very steep compared to the other dunes in the complex, especially

along the arms. The crest slopes down away from the lake. It has an altitude of 260 m and

located at 44.623994° N/ 86.233327°W with an approximate 25° orientation. The windward

basin of the dune and the leeward side are covered with large trees while the arms contain more

brush.

Despite being corrupted by human interference, we determined through stratigraphic

relationships that the relative ages are as follows from youngest to oldest: EA, EE, ED, EB=Ec

(Figure 4). The relative ages of EB and EC are unknown because they do not interact with each

other. EB lies beneath part of EA and the southern arm of EC covered by ED. For the purpose of

this study, we assume that EB and Ec formed at relatively similar times. We also preliminarily

inferred that EDC is younger than GPDC because the soil horizons do not appear to be as strong

or as well formed at GPDC. Soil pits were only dug on ED and EE because the rest of the dunes

showed too much human activity to produce reliable soil pits.

Lab Results

Soil data recorded in the field was used to determine trends and relationships in the lab.

We also gathered soil samples in the field for various soil analyses, including pH, clay content,

and the iron activity ratio. The results from these analyses were used to determine relative ages

for each dune and a calibrated age for each dune in GPDC. Our ages interpreted from laboratory

analyses differ slightly from the field results.

Horizon Color

Figure 5. The chroma and value of each dune increase as horizon depth increases across both complexes.

The color of the horizons are expected to increase in both chroma and value10 (Birkeland

1999). Color change is an indication of weathering and can be used to identify processes

occurring in the soil profile (Birkeland 1999). For example, minerals generally leach out of the

10 Saturation and brightness

E horizon and accumulate into the B horizon, so the E horizon is expected to have a white tint

while the B horizon should be orangeish red from iron deposits11.

The soil horizons for GPDC were initially determined to be A-E-B with GD displaying a

possible B212 horizon. EDC has an A-E horizonation; the soil pits never reached a B horizon.

Figure 5 shows the color determined using the Munsell color system, with chroma and value

plotted against each other. As the horizons get deeper across all dunes, both value and chroma

increase. The frequency of soil horizons exhibiting a certain value/chroma is represented by an

increase in point size. The E horizon has the greatest variation in color. There are clusters of

color points for each horizon, which indicates that the stratigraphy of all dunes can be compared

and developed under similar conditions (Arbogast et al. 2002). It is unclear if GD actually had a

B2 horizon because the points exists in the same color scheme as those in the B horizon.

While the horizons follow the expected pattern, there are no major color distinctions

between individual dunes or even between complexes. Color therefore shows that these sand

dunes are weathering in the expected manner but color cannot be used as an indicator of age

among the dunes themselves, most likely because they all stabilized over a short time span and

so there are distinguishable differences.

11 These colors are not exact based on the Munsell soil chart but are colloquial interpretations of color changes. 12 B2 refers to a subhorizon within the B horizon.

Horizon Development

A E0

5

10

15

20

25

30

A and E horizon thickness of GPDC

Pit1 Dune CPit2 Dune CPit1 Dune BPit2 Dune BPit1 Dune EPit2 Dune EPit1 DuneF 1Pit1 Dune F 2Pit2 Dune F 2Pit1 Dune DPit2 Dune DPit1 Dune GPit2 Dune G

Horizon

Horiz

on Th

ickne

ss (c

m)

Pit Informa-tion

Figure 6. There is no trend among A horizon thickness but two clusters based on depth emerge from the E horizon, corresponding to relative age.

Horizon thickness increases with age because there is more time for the horizons to

develop through weathering (Birkeland 1999). A study of chronosequences in various sand

dunes found that organic material increased for approximately 2000 years and that the depth of

calcium carbonate leaching, or the E horizon, also increased (Huggett 1998).

There is not a clear separation of trend among dunes when only the A horizon thickness

is considered. The thickness of the A horizon ranges from 3 to 16 cm and is variable across soil

pits. However a trend appears when the E horizon is considered. Soil pits reveal two clusters of

thickness for the E horizon. GC, GB, and GD all have shallow E horizons between 5 and 13 cm

while the thickness of GF, GE, and GG ranges from 20 to 25 cm. There is an approximate 8 cm

difference between the E horizon depths for GC, GB, and GD compared to GF, GE, and GG.

There is a connection between depth of E horizon and relative stratigraphic age (Figure

6). The dunes in the red shallower cluster, GB-GD, are the youngest stabilized GDPC dunes while

the dunes in the green deeper cluster consist of the back row of older dunes at GPDC, GE-GG.

GB and GD have shallower E horizons than A horizons. GC shows a slight increase in

depth between A and E horizons but it is not substantial. GF, GE, and GG all show a rapid increase

in soil thickness from the A to the E horizon. While the slopes of the lines were not analyzed for

significance, they show that the increase in depth from the A to the E horizon is much greater, or

steeper, in the older dunes than the younger ones. EDC was not included because it is only

possible to measure the depth of the A horizon, thus limiting the amount of comparison that can

be done.

Average Horizon Thickness

A E0

5

10

15

20

25

Average Horizon Thickness

Dune CDune BDune EDune FDune DDune G

Horizon

Thick

ness

(cm

)

Figure 7. The average horizon thicknesses of the depth of both pits from GPDC dunes.

The relationship between the two groups becomes clearer when the data from each pit is

averaged together. The E horizon of GC averages to 4 cm deeper than the A horizon. There is a 2

cm difference for GB and only a 0.5 cm difference in depth for GD. Meanwhile, the E horizon of

GE is 10.5 cm greater than the A horizon. GF has an average depth difference of 18.3 and the GG

difference is 10.5 cm. While the A horizons for each dune show varying depths, two clear

clusters emerge when the E horizon depth is considered. The thickness of the E horizon supports

the relative ages of the dunes in GPDC; the older dunes- GE, GF, GG- had longer to weather and

therefore a more developed E horizon than GC, GB, and GD.

Depth to B Horizon

0 1 2 3 4 5 6 70

5

10

15

20

25

30

35

40

R² = 0.982366100094544

Depth to B HorizonRelative Age

Dept

h (cm

)

Figure 8. Dunes plotted according to depth to the B horizon to infer relative ages with a strong

R2 value of 0.98.

There is an accepted relationship between depth to the B horizon and total time spent

weathering (Huggett 1998). Therefore depth to B horizon is a useful indicator of age among peer

sand landforms. The dunes in GPDC were arranged according to depth in order to create a new

set of relative ages (Figure 8). These new relative ages inferred through soil horizons can be

compared to the relative ages determined through stratigraphic field relationships (Table 1). The

ages in Figure 8 are relative and are not telling of the actual range between dates of stabilization

for each dune.

There is a strong linear trend (R²= 0.98) of increasing depth to the upper surface of the B

horizon throughout the complex. The relative ages from this depth test are as follows: GC, GD,

GB, GF, GG, GE. The dune ages roughly follow those preliminarily determined in the field. The

only differences are that this test finds GD to be younger than GB and GG to be younger than

GE. Again, EDC was not included in the depth studies because the pits did not appear to reach

the B horizon.

Since there can be discrepancies or errors in both field observations13 and lab tests14 as

determinants of age, the rest of the results in this paper will use both sets of ages (Table 1).

Table 1. Comparison of relative ages based on stratigraphy and soil horizonation. The ages range from 0 (active and youngest) to 6 (oldest).

Dune Name Stratigraphy Age Soil Horizon Age

GA 0 0

GB 1 3

GC 2 2

GD 3 1

GE 5 6

GF 4 4

GG 6 5

While the relative age ranking differs between the stratigraphic ages and the soil horizon

age, there is some agreement between the two. The youngest dunes (relative age 0-4) are those in

the front row of GPDC and the oldest dunes (relative age 4-6) are the three dunes in the back row

(Figure 3).

13 Field observations will be labeled “Stratigraphic Ages” in the following graphs.14 These lab test results will be referred to as “Soil Horizon Ages” in the following graphs

Total Clay

0 1 2 3 4 5 6 70

0.05

0.1

0.15

0.2

0.25

Average Clay Amount vs Age

Stratigraphic AgeSoil Horizon Age

Relative Ages

Perc

ent C

lay

(%)

Figure 9. There is no visible connection between clay and relative age for their complex, regardless of stratigraphic or soil horizon determinants.

Clay moves from the upper soil horizons into the lower horizons through weathering

because clay minerals transform into different products after reacting with other elements in the

soil. Clay is often used to reflect the long-term leaching environment of the soil because of this

downward migration (Birkeland 1999).

There is no trend between amounts of clay and age for either age ranking. The dunes

exhibit fluctuations of clay amounts that cannot be connected to relative age or time spent

weathering.

The lack of a connection between age and clay could be due to the fact that there are a lot

of properties that affect clay development. Clay reacts with a variety of minerals within the soil,

making its weathering patterns difficult to follow. For example, an excess of carbonate in the soil

can prevent clay migration from occurring while increased temperature and moisture can

increase the rate of transformation (Birkeland 1999). Additionally, the parent material is sand,

which naturally does not have a high clay content and so there may not enough clay in the soil

for a clear trend to develop.

pH

Elberta E Elberta D Dune C Dune B Dune D Dune F Dune E Dune G0

1

2

3

4

5

6

7

Stratigraphic Age versus pH Values

A AB B BC

Relative Age (youngest to oldest)

pH

Figure 10. The pH trends from each horizon plotted against relative age determined through the field. EDC and GPDC are not connected by age.

Elberta E Elberta D Dune C Dune D Dune B Dune F Dune G Dune E0

1

2

3

4

5

6

7

Soil Horizon versus pH Values

A AB B BC

Relative Age (youngest to oldest)

pH

Figure 11. The pH trends from each horizon plotted against relative age determined through the lab. EDC and GPDC are not connected by age

pH can be a good indicator of age because pH deceases as “carbonate minerals weather

and large quantities of Ca and Mg are leached from the surface soil” (Lichter 1998). This means

that pH decreases with age until it reaches an equilibrium point (Huggett 1998). Lichter found

that it takes approximately 400 years after a dune forms and a forest develops on it for pH to

reach an equilibrium point at his comparable study site (1998).

Figures 11 and 12 show the average pHs of the two pits for each dune and the change in

pH across horizons. There is a negative correlation between horizon depth and acidity; the pH for

the horizons in all of the GPDC dunes become increasingly basic as the horizons get deeper. In

other words, the A horizon is more acidic than the B horizon. The pH of each horizon remains

constant across all of the GPDC dunes, except for GC. GC displays a decreasing trend in pH when

compared to the rest of the dunes in GPDC. Additionally, there is no visible relationship between

ED and EE because there are not enough data points for a trend to emerge. The pH of ED and EE is

similar to GC but these dunes cannot be compared because they exist of different parent material.

The different pH at GC shows that this dune may not have reached the same equilibrium

point as the rest of the dunes at GPDC. Therefore, this dune may still exist within the 400 year

development period determined by Lichter (1998). The straight line for both the E and B

horizons in the rest of the dunes indicate a minimal change in pH values, which could mean that

these dunes have stabilized and reached this equilibrium. It could also mean that these dunes all

formed within a small time frame and so their pH values are indistinguishable. This seems less

likely than the former theory, taking into account the differences in the other tests performed

which points to distinct periods of time between the stabilization of each dune in the complexes.

Height

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 60

50

100

150

200

250

300

f(x) = 4.21428571428571 x + 227.833333333333R² = 0.104816773895676

Stratigraphic Age versus Height

Relative Age

Heig

ht

p= 0.23356

Figure 12. Stratigraphic age does not have a strong or significant relationship to height.

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 60

50

100

150

200

250

300

R² = 0.329450472242575

Soil Horizon Age versus Height

Relative Age

Heig

ht (m

)

p= 0.531275

Figure 13. The soil horizon age does not have a strong or significant relationship to height.

There is not much research about dune height as an indicator of age because height can

be impacted by many factors, such as sand supply, wind energy, obstructions, and vegetation

(Gares and Nordstrom 1995; Hansen et al. 2009). However, we looked to see if there was a

connection because in the field the older three dunes in the back of GPDC appeared larger than

the younger dunes. EDC was not used in this comparison because it lies on a bluff, complicating

the data.

The relationship between dune height at the crest and relative age is weak for both age

orders (R²= field 0.13; lab 0.33). However, soil horizon age is a stronger indicator for height than

stratigraphic ages, shown by a higher R2 value of the soil horizon line. The p-value for both

graphs is greater than 0.05 for both age types (p= field 0.23, lab 0.53) and so overall height is not

a significant determinant for age.

While there is no statistical significance of height in relation to age, it appears that the

GPDC dunes in the back of the complex are higher than those in the front row. In other words,

height and age seem to increase as the dunes move eastward but not enough to be an indicator of

age. This could mean that there was a greater sediment supply during the formation of E, F, and

G than during the formation of B, C, and D. There is a limited relationship between age and

height, however, because height depends on environmental conditions and does not continue to

develop after stabilization.

Iron

0 1 2 3 4 5 6 7 80

0.05

0.1

0.15

0.2

0.25

0.3

f(x) = 0.00545968194521401 x + 0.0909480549073216R² = 0.108925276605002

Stratigraphic Age Versus FeD

Relative Age

ppm

Figure 14. Ppm of Fed shows a positive trend with an R2 value of 0.256 when plotted against relative ages determined in the field.

0 1 2 3 4 5 6 7 80

0.05

0.1

0.15

0.2

0.25

0.3

f(x) = 0.00745422843727672 x + 0.0818389057874859R² = 0.201136517673045

Soil Horizon Age versus FeD

Relative Age

ppm

Figure 15. Ppm of Fed shows a positive trend with an R2 value of 0.201 when plotted against relative ages determined in the field.

GPDC

EDC

GPDC

EDC

0 1 2 3 4 5 6 7 80

0.01

0.02

0.03

0.04

0.05

0.06

R² = 0.292901191113332

Stratigraphic Age versus FeO

Relative Age

ppm

Figure 16. Ppm of Feo shows a slight positive correlation with relative ages determined in the

field (R2 = 0.293).

0 1 2 3 4 5 6 7 80

0.01

0.02

0.03

0.04

0.05

0.06

R² = 0.4654176133043

Soil Horizon Age verus FeO

Relative Age

ppm

Figure 17. Ppm of Feo shows a slight positive correlation with relative ages determined in the

lab (R2 = 0.465).

0 1 2 3 4 5 6 7 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

f(x) = 0.0113143880832996 x + 0.277515707648166R² = 0.0717067462626654

Soil Horizon versus Fe Ratio

Relative Age

Activ

ity R

atio

Figure 18. Total iron activity ratio does not show a correlation with relative ages determined in

the lab.

0 1 2 3 4 5 6 7 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

R² = 0.0700874184898114

Stratigraphic Age verus Fe Ratio

Relative Age

Activ

ty R

atio

Figure 19. Iron activity ratio does show a correlation with relative ages determined in the field

It is known that iron can translocate downward through a soil profile; this often occurs in

sandy, high latitude, and cool-climate forest conditions, such as the dunes in this study

(Birkeland 1999). Unbound iron in the upper horizons ideally transforms into bound iron.

Therefore, the ratio of Feo (unbound iron) to Fed (unbound iron plus bound iron), or the iron

activity ratio, reveals the level of oxidation within the B horizon. This can be interpreted as time

spent weathering.

As age and time increase, the iron activity ratio is supposed to decrease. FeO should

continually decrease with age as Fed increases because Feo transforms into iron oxides over time,

leaching out of the upper horizons and accumulating in the B horizon in a new bound form.

Some researchers only look at the accumulation of Fed in the B horizon but the ratio provides

information about the transformation process (Dethier et al. 2012).

Figures 14 and 15 reveal the amount of Fed removed from the samples. Figures 16 and 17

represent the amount of FeO extracted from the soil samples. Figures 18 and 19 combine both of

these tests to reveal the activity ratio, or the transformation of unbound iron to iron oxides. The

numbers closer to zero are supposedly more oxidized and a negative trend is expected. However,

there is an upward trend for all three tests.

The positive connection between iron and age becomes stronger with the outliers

removed15. The positive trend between Fed and relative age becomes stronger with the outlier,

Pit2 from P2GD, removed (R2 = field 0.256 versus 0.260; lab 0.201 versus 0.481). The positive

trend for Feo also becomes stronger when the Pit 2 ED outlier is removed (R2= 0.293 field versus

0.420; lab 0.465 versus 0.624). The outlier in the ratio trends in P2ED; the Fed outlier is

“absorbed” because Fed is much smaller of a figure compared to Feo. When the outlier is

removed, the iron activity ratio goes from having no trend (R2= field 0.070; lab 0.072) to a

relatively strong positive trend (R2= field 0.436; lab 0.442).

The iron activity may have increased over time instead of decreasing as expected because

there is not enough material in the sandy soil for the unbound iron to react with in order to create

15 All of the relationships were determined with EDC as the youngest dunes and so the results could change if the EDC ages change.

the iron oxides. Therefore, FeO might be accumulating in the B horizon rather than transforming

into new forms in this environment. FeO has the strongest correlation seen through high R2 values

and so this accumulation could be what is creating problems with the relationship.

Another hypothesis is that the influx of iron from organic material on these dunes occurs faster

than the Feo can convert to Fed. Since sand has a very permeable nature, it is easier for iron to

quickly move through the horizons than in other environments (Hugget 1998). Additionally, this

method of measuring iron activity has not been tested in sandy parent material and so the test

might not be a good indicator of age and weathering for this parent material.

Approximate Absolute Ages

200 400 600 800 1000 1200 1400 1600 1800 2000 22000

5

10

15

20

25

30

35

40

Dune C

Dune D

Dune B

Dune FDune G

Dune E

Ridge Age and Depth to B Horizon

Dune Age (yr)

Dept

h (c

m)

Figure 20. Calibrated ages determined by using an equation for the depth to the B horizon.

Lichter (1998) charted the depth to the B horizon against dune age determined through

radiocarbon dating, resulting in a single logarithmic equation with a very strong fit (R²= 0.98, f

(t) = -77.77 + 34.54logt). We substituted the depth from GPDC for f (t) and solving for t using

Lichter’s equation (1998). The resulting graph (Figure 20) follows the single log chronofunction.

The ages range from 347.63 years old for GC to 2033.94 years old for Dune 3.

The lab ages are presumed to be correct because they are created using the absolute ages

in Lichter. Both Lichter’s study and the depth to B horizon test in this study have very strong R²

values and so there is a strong likelihood that these ages are correct.

These calibrated ages also make sense in the context of the region because it means that

the dunes all formed after the Nipissing Transgression. This study agrees with findings that the

most recent period of dune building is fairly recent: within the last 1500 BP cal years (Lepcyzk

and Arbogast 2004; Hansen et al. 2006; Arbogast 2000). The oldest dune in GPDC, GE, is around

2033 years old but the rest of the dunes fall within that 1500 year time frame. Geographic

variability in dune formation may account for the GE age because none of the lake-plain dune

complexes examined in previous studies exist as far north as GPDC. Unfortunately, these

calibrated ages to not contain EDC and so the following test was completed to determine the

relationship between the two complexes.

Element Concentration

Soils develop until they reach an equilibrium point and will remain at this equilibrium

given that environmental conditions remain stable (Huggett 1998). A study by Lichter (1998)

looks at elemental concentrations in the upper 15 cm of the soil profile as an indicator of soil

development. According to Lichter, various elements (namely Ca, Mg, K, P, Zn, Mn, Fe, Al, and

V) deplete to low asymptotic levels and “provide a good fit for weathering” (1998). He presents

graphs of these elements that have a strong fit to a negative exponential curve when compared to

age and are statistically significant. However, his trends are strengthened by a few concentrations

that correspond to older dunes (i.e. 4000 years old).

Upon closer examination, Lichter’s study turns out to be difficult to replicate because,

while many of his final assertions and conclusions are valid, he makes several assumptions that

strengthen his results but may not be translatable to other studies. He also uses a method that is

difficult to replicate and so we followed the standard EPA method for acid digestion. See

Methods section for details. Because of this, we were not able to directly compare our results

because they did not align numerically. Instead, we compared the shape of our graphs with his to

determine the relative age range for EDC and GPDC (Figures 24 and 26). The data was not

converted to match Lichter’s units because that would skew the data and was unnecessary

because we were comparing shapes of the graphs.

The elemental concentrations are reported individually for each element and are

organized by the soil horizon age structure with EDC presented as the youngest complex. The

concentrations of beach sand were not included in the graphs because it was too variable; the

influence of current lake activity on the concentration of elements in current beach sand is

unknown and the data was inconsistent. For future tests, we should collect sand from the active

dune face to limit the shore line influence of waves and sand replenishment from the lake.

We chose to focus on Ca and Mg because they have the strongest R2 values out of the

reported element concentrations (Table 1 in Appendix). See Figures 3-6 in the Appendix for

graphs of the remaining elements that also have significant significance and similar trends (Fe, P,

K, Ti). The rest of the elements were not statistically significant and so their graphs are not

presented. This does not mean that these elements are not indicative of soil weathering but

simply that they did not correspond to Lichter’s results.

0 1 2 3 4 5 6 7 8 9 100.000

500.000

1000.000

1500.000

2000.000

2500.000

3000.000

3500.000

4000.000

4500.000

f(x) = 2152.79702744115 exp( − 0.288358245575133 x )R² = 0.550666658448467

Soil Horizon versus Calcium

Relative Age

Conc

entra

tion

(ppm

)

Figure 23. The concentration of Ca has a significant relationship with age when the data is organized by the soil horizon age structure.

Figure 24. The box represents where the data from Figure 23 may fit on Lichter’s graphcomparing Ca quantity and age.

p= 0.011

0 1 2 3 4 5 6 7 8 9 100.000

100.000

200.000

300.000

400.000

500.000

600.000

700.000

f(x) = 479.325713945194 exp( − 0.21494229594755 x )R² = 0.706748330226907

Soil Horizon versus Magnesium

Relative Age

Conc

entra

tion

(ppm

)

Figure 25. The concentration of Mg has a significant relationship with age when organized by soil horizon age.

Figure 26. The box represents the place where the line from Figure 25 would best fit on Lichter’s graph of quantity versus age.

Figures 23 and 25 show the concentrations for Ca and Mg without any normalization of

the data. Both graphs display a negative exponential trend and the relationship between

concentration and soil horizon age is significant (Ca R2 = 0.5507, p= 0.011; Mg R2 = 0.71, p=

0.002). As time increases, the concentration of Ca and Mg in the upper horizon of soil decreases.

p= 0.002

The shapes of these two graphs fit on Lichter’s graphs just before the asymptotes are

reached. Ca rapidly depletes on Lichter’s graph before leveling out at approximately 700 years.

The Ca in our study has not yet reached an asymptote and exists at the point on the curve where

the line is leveling out. The age range of the complexes using Ca is between 500 and 1200 years

(Figure 24). Mg also quickly reaches an asymptote in Lichter’s study. The Mg concentrations fall

on his curve between 400 and 1200 years (Figure 26). EE is an outlier for Ca and Mg, along with

several other elements but it does not limit the connection that can be drawn between element

levels and time. The fit to the line is still significant after EE was removed from the analysis.

Ca and Mg have the strongest R2 values out of the rest of the elements because Ca and

Mg are extremely mobile and are often among the first elements to leach from a profile

(Birkeland 1999). They deplete at a fairly fast rate compared to other elements and reveal the

most developed trend for our complex. The age ranges reveal that EDC and GPDC stabilized

later overall than Lichter’s complex and so GPDC and EDC have had less time to develop than

Lichter’s and less time for elements to decrease to an asymptote. Since Ca and Mg move first

through a profile their relation to age is clearer on a tight timeline than other elements.

These age ranges are consistent with earlier trends determined from this study. The

element concentrations reveal that the dunes formed between 500 and 2000 years ago and these

ages fit with the calibrated ages determined by the depth to B horizon (Figure 20). The beginning

of podsolization16 is marked by the rapid leaching of Ca and Mg from the weathering profile.

Podsolization also corresponds to a decrease in pH in the upper horizons (Lichter 1998). The

depreciation of Ca and Mg in GPDC correspond to the more acidic pH in the complex, compared

to the basic pH of the EDC horizons. While there were only two data points for EDC, the

element concentrations were consistently higher than those reported for GDPC. According to

16 The movement of elements downward from the zone of weathering to the E horizon (Birekland 1999).

Lichter, this means that EDC has not had has much time to weather and the dune complex is

younger overall than GPDC. This also explains the lack of a visible B horizon, supporting the

assumption that it has not yet developed. The element concentration trends are stronger when

organized by soil horizon age rather than stratigraphic age and the age ranges make sense when

compared to the ages calibrated from depth to the B horizon.

Wind Direction

Figure 21. Wind direction of GPDC Figure 22. Wind direction of Elberta complex

Wind direction could be a telling factor for dune stabilization because similar orientations

could connect dune complexes, strengthening the formation histories of dunes across Lake

Michigan. The current prevailing wind direction along the Lake Michigan coast come from the

west and northwest, resulting in an orientation between 90° and 135°. GC and the currently

forming GA are forming from a western wind and GD shows formation from wind coming from

the northwest. The rest of the dunes in GPDC, however, appear to form from winds coming from

the SW. This provides evidence that the prevailing wind direction changed slightly since the

older dunes formed; GC and GD formed with the same wind influence as modern dunes. Periods

of dune migration could be influenced by storminess or seasonality of winds (Fisher and Loope

2005). There is evidence that most modern dune growth occurs during the fall when “westerly

winds are the strongest” (Hansen et al. 2010) which is corroborated by the western formation of

GA. While little evidence exists to suggest that wind direction completely changed, a large storm

coming for the north or south could explain the differing orientations. A changing wind

direction could explain also the lobes on GC. The dunes in the Elberta complex all lie in the same

southwest direction. This difference in orientation (and possibly the wind regime) could be

important in determining the relative timing between the two dune complexes and place their

formation within the larger context of the paleoclimate (Hansen et al. 2009; Kocurek and Ewing

2005).

The dunes in the Hansen et al. study lie in the same western orientation as GA and GC;

Hansen’s dunes and these two GPDC dunes were all found to have stabilized within the last 500

years (2010). The connection between both ages and orientation in these two complexes show

that wind direction could potentially be used to determine the relative ages of dunes. However,

wind direction is more indicative of formation and activation than stabilization timing.

Comparison of the Complexes

200 400 600 800 1000 1200 1400 1600 1800 2000 22000

5

10

15

20

25

30

35

40

Dune C

Dune D

Dune B

Dune FDune G

Dune E

Ridge Age and Depth to B Horizon

Dune Age (yr)

Dept

h (c

m)

Figure 23. Calibrated ages of GPDC fitted with the age range for EDC, determined through element leaching concentrations.

The elemental concentrations allow the two complexes to be compared, but only using

relative age ranges. These age ranges place the stabilization of EDC after GPDC or occurring at

the same time as the front row of GPDC (Figure 23). Some studies found that northern dune

complexes are younger by several hundred years than more southern dunes and our study follows

this finding (Arbogast et al. 2002; Loope and Arbogast 2000).

As a continuation of strengthen the age relationship between GPDC and EDC, we looked

at the soil horizon information from the field, ordering all of the dunes solely by horizon

classification through pictures taken in the field. See Figure 7-14 in the Appendix for these

images. This included rethinking the classification of soil horizons. It appears that not all of the

dunes have developed a distinct E horizon, which may indicate less weathering than previously

determined. We organized the rest of the information gathered from the soil pits by these horizon

classification ages and looked for trends (Table 2).

Table 2. Soil information organized by the new horizon classification ages.

Relative Age 1 2 3 4 5 6 7 8

EDC rangeGPDC range

Dune Name GC GD GB EE ED GF GG GE

A Horizon Depth (cm) 5 10 20 20 20 10 7 10

Horizon Classification A/C A/B A/B A/B A/B A/E/B A/E/B A/E/B

Color of B Horizon 5/4 5/4 or

4/6

5/4 or

5/6

4/4 5/4 or

5/5

5/6 5/6 6/6 or

4/6

Depth to B Horizon (cm) 10 13 22 22 22 28 31 38

   

The trends seen in the table are subjective and all connections are inferred through

information available in Table 2. The depth to B horizon is linked to horizon classification, since

the depth increases as the ranked age increases. This provides further evidence that depth to the

B horizon is an appropriate indicator of age and strengthens the inference that the soil horizon

ages are correct, rather than the stratigraphy ages. Color, on the other hand, does not work well

as an indicator of age. There is no strong difference in color between any of the dunes. This

could be because the ages of all of the dunes are too similar for color to have changed

dramatically. The negligible change in color of the B horizon could explain why the iron activity

ratio did not work as an indicator of age for these dunes. It appears that the A horizon is

cannibalized by the B horizon at a certain threshold, possibly around 20 cm, because the A

horizon increases and then decreases in depth while the B horizon continually increases. This

observation connects with the thickness trends of each horizon (Figure 7).

Organizing the dunes in this way allows us to continue to compare the ages of EDC and

GPDC. It appears that EDC stabilized after the back row of GPDC – GE, GF, and GG- but before

or at the same time as the first row- GB, GC, and GD. The soil properties create an age structure

that is very compatible with the soil horizon age structure and element leaching age ranges and

so it is not going to be analyzed using the lab results. Instead, this further corroborates the soil

horizon ages as the correct, or strongest, relationship. The main difference is that EDC was

placed between the two rows of GPDC but the possibly different parent materials at both

complexes could explain this inconsistency.

EDC stabilized later than GPDC. This relationship is established by the connection

between depth to B horizon, pH, element leaching, and overall weathering. However, there are

some discrepancies that show that soil horizon do not necessarily develop linearly and that there

are many factors that influence weathering and trends within the profile.

Understanding Stabilization Factors

Many factors play a role in dune activation and stabilization, complicating the soil and

geomorphic record. This study focuses on stabilization because the tests use soils at the surface,

which does not provide information about activation. Dunes are sensitive to different types of

disturbances; in particular dunes are sensitive to changes in wind energy, sand supply, and

vegetation related to climate (Yizhaq et al. 2009). These fluctuations and cycles account for

different states of stabilization within the same complex, as seen in the non-concurrent

stabilization of the EDC and GPDC dunes (Hansen et al. 2010; Lepcyzk and Arbogast 2005;

Yizhaq et al. 2007). This reaction to environmental factors is more complicated than simply a

response to lake level. There were no major transgressions or changes in lake level within the

past 1500 years (Appendix Figure 1) and yet this is when we see the most dune activity in the

two complexes. The authors of one study found that dunes in Holland, MI migrated through

reactions to both high and low lake levels (Arbogast et al. 2002). GPDC and EDC reveal similar

sensitivity and show that the connection between lake level, sediment supply, and energy is

complicated. Additionally, our interpretation that EDC stabilized last or around the same time as

the front row of GPDC shows that perched dunes may react to different conditions than lake-

plain dunes. Since these dunes exist geographically close, they should be experiencing the same

environmental conditions. These dunes may be reacting to more localized disturbances.

The thresholds for activation and stabilization also vary within the complexes. Both

GPDC and EDC have active and stabilized dunes coexisting. Therefore it seems that whatever

factors that start a new dune or reactive a preexisting dune are not enough to reactivate all of the

dunes in the complexes. The activation thresholds are higher or than stabilization thresholds once

the dune becomes forested.

Sources of Error

There are inherently sources of error in any study that uses quantitative data and samples

with unknown environmental factors. For example, the incongruities in soil data can be

explained by the properties of soil development: soils often do not develop in a steady rate and

factors, such as weather, animals, and vegetation, can affect development of soil evolution

(Huggett 1998). This uneven rate can affect tests such as pH and clay amount. Human error

may have been involved in the description of each soil profile, which accounts for the new

interpretation seen in Table 2.

In the lab, sources of error came from minute differences in lab technique across tests.

The amount of soil used for each test was accurate to the tenth of a gram. The sand was manually

sieved for the clay test and the magnetite was manually taken out for the Fe tests. Sources of

error also come from the AAS machine used for the Fe tests; the flame had to be continually

checked against standards for accuracy but small changes could have thrown off the results.

Additionally, there were a limited number of data points in this study. The relationships

determined through these tests could be strengthened or altered with the addition of more data

from similar transitional dune complexes. The small sample size in this study makes it even more

difficult to tease out small trends in stabilization.

Sources of Error within the Element Concentration Component

Lichter’s study poses a unique challenge because his results were extremely strong but he

made assumptions and used unclear methods that made his overall study difficult to follow with

confidence. For example, he uses a mass-balance model equation to account for changes in total

soil volume or strain. He uses the strain to normalize the concentrations of elements to account

for either dilation17 or collapse of the soil. The equation calls for comparison between an

immobile element in the parent material and the immobile element in the sample. Lichter chose

titanium as his immobile element with little reasoning and uses the y-intercept, calculated from

his negative exponential concentration equations instead of the zero point for the parent material.

This substitution assumes that there is little to no error in the elemental depletion calculations.

We did not feel comfortable making this leap because the majority of our initial graphs

comparing concentrations to age did not have a strong relationship, according to the R2 values.

Additionally, the lab did not report the concentrations of Ti and none of our elements appeared to

be immobile enough to confidently use in the mass-balance model. Lastly, Lichter provides a

graph of strain versus ridge age and there is no relationship between the two in the first 1000

years, which is the age range in which we assume the majority of GPDC and EDC exist. He

17 Expansion of the soil due to factors such as root growth or animal tunneling (Lichter 1998).

determines that there is an overall 121% increase in strain but does not provide any information

on the confidence of this number, such as R2 or a p value (1998). Since his data seemed scattered

and lacking statistical value, we chose not to use soil dilation in the study. This meant that we

could not compare the data numerically and instead looked at shapes, as mentioned in the results.

The accuracy of the negative exponential line on Lichter’s graphs does not appear to be

high for the majority of the data points that exist within the first 1000 years. It is strengthened by

the presence of a few much older points between 2000 and 4000 years old (1998). The

connection between chemical depletion and age may only be useful for the creation of long

chronosequences. Without these data points, many of his younger data points appear scrambled

and do not display an obvious trend. In order to mimic this, we needed to collect some samples

further away from the dune complex or dug a few pits deeper in order to mimic this purposeful

inclusion of older samples. This hindsight knowledge could improve future attempts to use

elemental leaching trends to create chronosequences.

There are also issues associated with developing a chronosequence. It is difficult to focus

on one property plotted against time because that assumes that all other factors that influence soil

development are being held constant (Huggett 1998). Lichter attempts to artificially create this

constancy by factoring in the soil strain. However, there are other factors such as changes in

vegetation or topography that are unknown when creating a chronosequence that cannot be

ignored.

Further Studies

The ages and relationships of the dunes in this study can be strengthened through further

tests, as well as the interaction between stabilization and environmental factors. While we were

able to determine relative relationships through calibrated age ranges, this study did not

definitively determine the age of the dunes. Future analysis of the OSL samples would be

essential in understanding the formation of the dunes because it will give absolute dates for

stabilization. The results of this study can then be definitively determined.

A more in-depth look into the dune complexes surrounding GPDC and EDC will also

help understand the timing of migration within the paleoclimate as it is known now and narrow

down the main instigators of dune movement.

Conclusion

Through this study, we determined the relative ages of dunes within two Michigan dune

complexes. The calibrated ages from GPDC allow us to place these dunes within the

paleoclimate of the region. EDC and GPDC generally fit with conclusions drawn by previous

studies. Both of these complexes formed after the Nipissing Transgression and within the past

2000 cal. years BP, as seen by the depth to B horizon and element concentrations, especially Ca

and Mg.

It is difficult to tell if lake-plain dunes and perched dunes are affected by the same

triggers because the stabilization connection between GPDC and EDC is not entirely clear. EDC

is younger than GPDC but we must remember that only the youngest two dunes were included in

the lab tests for EDC. Perched dunes could experience different environmental factors because of

their elevation. Broadly, the results from each of the tests exist within the same range. The color

relationships between the dune complexes is too similar to distinguish any age trend. pH could

potentially provide valuable information about stabilization once definitive information about pH

thresholds in sand dunes in northern Michigan is known. There was no relationship with clay and

further tests need to be done on other minerals or compounds in the soil to see if better indicators

exist. The orientation of the dunes shows variation in wind energy during the creation of the

dunes, which could be valuable when compared with other dune complexes in Michigan.

Through these tests, we learned that depth to B horizon seems to be the best indicator of age out

of these tests. The calibrated ages reveal that GPDC began to stabilize approximately 2000 years

ago and element leaching shows that EDC either stabilized after GPDC or while some of the

younger dunes in GPDC were still stabilizing. While these individual tests do not necessarily

reveal the ages of the dunes, together they create an understanding of the past stabilization

history.

Lake-plain dunes supposedly follow the same stabilization and activation trends as

perched dunes. They both enlarge during high lake intervals but this is not seen in the current

data of this study because most dunes stabilized during a period of fairly normal lake levels

(Arbogast and Loope 1999; Arbogast and Loope 2000; Arbogast et al. 2002). Dunes can also

move due to localized disturbances and changes in the environment; this movement continues in

to the present and can mask or confuse information seen in the soil profile (Van Oort et al. 2001).

We also tested the potential of various dating techniques, based on availability and

accuracy. These can be used if the funds or materials for other methods, such as radiocarbon

dating, ground-penetrating radar, and OSL dating, do not exist. The methods used in this study

are cheaper and more accessible than other methods while still establishing relative and

calibrated ages. The methods create a general picture of how lake dunes are reacting to the

environment and each other. pH and horizon thickness both proved to be fairly accurate

indicators of understanding dune weathering. Additionally, we found that viewing chemical

depletion as an indicator of time spent weathering has potential as a way to create soil

chronosequences for dunes. The method found in Lichter needs to be polished in order to be

replicated. For example, it would be helpful to know the reasoning behind some of the

assumptions that Lichter makes and to see the results without any normalization or reformatting

of data. However, looking at movement of chemicals in the top 15 cm of the soil as an indicator

of weathering within the entire profile is unique and could be very helpful in understanding dune

activity.

Once we learn the absolute ages of GPDC and EDC, we can say more about the

comparison between dune types and the accuracy of relative dating methods. The geomorphic

past of the Lake Michigan dunes is complicated, especially since there are so many factors at

play but hopefully the more that we learn about GPDC and EDC, the more we will understand

these factors. It will especially be interesting to see the role that environmental conditions and

geography play in creating these two dune types. GPDC and EDC especially can provide

valuable information because their adjacent position lessons the role of geography and isolates

the impact of environmental factors.

Works Cited

Anderton, John B., Loope,Walter L. 1995. "Buried Soils in a Perched Dunefield as Indicators of Late Holocene Lake-Level Change in the Lake Superior Basin." Quaternary Research Quaternary Research 44 (2): 190-199.

Arbogast, Alan F, Schaetzl, Randall J, Hupy, Joseph P, Hansen,Edward C,. 2004. "The Holland Paleosol: An Informal Pedostratigraphic Unit in the Coastal Dunes of Southeastern Lake Michigan." Can.J.Earth Sci.Canadian Journal of Earth Sciences 41 (11): 1385-1400.

Arbogast, Alan F., Loope,Walter L.,. 1999. "Maximum-Limiting Ages of Lake Michigan Coastal Dunes: Their Correlation with Holocene Lake Level History." Journal of Great Lakes Research Journal of Great Lakes Research 25 (2): 372-382.

Arbogast, Alan F., Packman,Susan C.,. 2004. "Middle-Holocene Mobilization of Aeolian Sand in Western Upper Michigan and the Potential Relationship with Climate and Fire." The Holocene 14 (3): 464-471.

Arbogast, Alan F., Scull, Peter, Schaetzl, Randall J., Harrison, Joseph, Jameson, Thomas P.,Crozier, Scott,. 1997. "Concurrent Stabilization of some Interior Dune Fields in Michigan." Physical Geography 18 (1): 63-79.

Arbogast, Alan F., Edward C. Hansen, and Martin Van Oort. 2002. "Reconstructing the Geomorphic Evolution of Large Coastal Dunes Along the Southeastern Shore of Lake Michigan." Geomorphology 46: 241-255.

Arbogast, Alan F. 2000. "Estimating the Time since Final Stabilization of a Perched Dune Field Along Lake Superior." The Professional Geographer 52 (4): 594-606.

Barnhardt, W. A., Jaffe, B. E., Kayen, R. E., Cochrane,G.R.,. 2004. "Influence of Near-Surface Stratigraphy on Coastal Landslides at Sleeping Bear Dunes National Lakeshore, Lake Michigan, USA." Journal of Coastal Research 20: 510-522.

Birkeland, Peter W. 1999. Soils and geomorphology. New York, NY [u.a.]: Oxford Univ. Press.

Dethier, D. P., Birkeland, P. W. & McCarthy, J. A. 2012. “Using the accumulation of CBD-extractable iron and clay content to estimate soil age on stable surfaces and nearby slopes, Front Range, Colorado”. Geomorphology 173–174: 17–29

Environmental Protection Agency (EPA). 1996. “Method 3050B: Acid Digestion of Sediments, Sludges, and Soils”. Accessed February 2015. http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/3050b.pdf

Fisher, Timothy G., Loope,Walter L.,. 2005. "Aeolian Sand Preserved in Silver Lake: A New Signal of Holocene High Stands of Lake Michigan." The Holocene 15 (7): 1072-1078.

Fisher, Timothy, Loope, Walter, Pierce, William,Jol, Harry,. 2007. "Big Lake Records Preserved in a Little Lake's Sediment: An Example from Silver Lake, Michigan, USA." Journal of Paleolimnology 37 (3): 365-382.

Gares, Paul A, Nordstrom,Karl F,. 1995. "A Cyclic Model of Foredune Blowout Evolution for a Leeward Coast: Island Beach, New Jersey." Annals of the Association of American Geographers. 85 (1): 1.

Google Maps, 2014. “Benzie County, MI”. Map. Accessed September 2014. www.maps.google.com

Hansen E., DeVries-Zimmerman S., van Dijk D.,Yurk B.,. 2009. "Patterns of Wind Flow and Aeolian Deposition on a Parabolic Dune on the Southeastern Shore of Lake Michigan." Geomorphology Geomorphology 105 (1-2): 147-157.

Hansen, E.C., Arbogast, A.F., van Dijk, D.,Yurk, B.,. 2006. "Growth and Migration of Parabolic Dunes Along the Southeastern Coast of Lake Michigan." Journal of Coastal Research: 209-214.

Hansen, Edward C., Fisher, Timothy G., Arbogast, Alan F., Bateman,Mark D. 2010. "Geomorphic History of Low-Perched, Transgressive Dune Complexes Along the Southeastern Shore of Lake Michigan." Aeolian Research 1 (3-4): 111-127.

Hugenholtz, C. H., Wolfe,S.A.,. 2005. "Recent Stabilization of Active Sand Dunes on the Canadian Prairies and Relation to Recent Climate Variations." Geomorphology –Amsterdam 68 (1-2): 131-147.

Huggett, R.J., 1998. “Soil chronosequences, soil development, and soil evolution: a critical review.” Catena 32: 155-172.

Kocurek, Gary, and Ryan C. Ewing. 2005. "Aeolian dune field self-organization - implications for the formation of simple versus complex dune-field patterns". Geomorphology. 72 (1): 94-105.

Lepczyk, Xiomara Cordoba, Arbogast,Alan Ford,. 2005. "Geomorphic History of Dunes at Petoskey State Park, Petoskey, Michigan." Journal of Coastal Research 21 (2): 231-241.

Lichter, John. 1998. "Rates of Weathering and Chemical Depletion in Soils Across a Chronosequence of Lake Michigan Sand Dunes." Geoderma 85: 255-282.

Loope, W. L., Fisher, T. G., Jol, H. M., Goble, R. J., Anderton, J. B., Blewett,W.L.,. 2004. "A Holocene History of Dune-Mediated Landscape Change Along the Southeastern Shore of Lake Superior." Geomorphology -Amsterdam-. 61 (3-4): 303-322.

Loope, W.L, and Arbogast, A.F. 2000. "Dominance of a ~150-Year Cycle of Sand-Supply Change in Late Holocene Dune Building Along the Eastern Shore of Lake Michigan." Quaternary Research 54: 414-422.

Lovis, William A., Alan F. Arbogast, and G. William Monaghan. 2012. The Geoarchaeology of Lake Michigan Coastal Dunes. East Lansing: Michigan State University Press.

Mason, Jon P., Swinehart, James B., Loope,David B.,. 1997. "Holocene History of Lacustrine and Marsh Sediments in a Dune-Blocked Drainage, Southwestern Nebraska Sand Hills, U.S.A." Journal of Paleolimnology 17 (1): 67.

Mason, Joseph A., Swinehart, James B., Goble, Ronald J., Loope, David B., 2004. "Late-Holocene Dune Activity Linked to Hydrological Drought, Nebraska Sand Hills, USA." The Holocene 14 (2): 209-217.

McFadden, L. D. & Hendricks, D. M. Changes in the content and composition of pedogenic iron oxyhydroxides in a chronosequence of soils in southern California. Quaternary Research 23, 189–204 (1985).

McKeague, J. A. & Day, J. H. Dithionite- and oxalate extractable Fe and Al as aids in differentiating various classes of soils. Can. J. Soil. Sci. 46, 13–22 (1966).

Mehra, O. P. & Jackson, M. L. Iron oxide removal from soils and clays by a dithionite-citrate system buffered with sodium bicarbonate. inProc. 7th nat. Conf. Clays. 5, 317–327 (1960).

Olson, Jerry S., 1958. “Lake Michigan dune development: Lake-level, beach, and dune oscillations”, The Journal of Geology 66, 473-483.

Science Education Resource Center (SERC) at Carleton College, 2012. “The Coastal Archaeology and Dune Geoarchaeology of Lake Michigan”. Accessed 12 December 2014. http://www.slideshare.net/sercuser/the-coastal-archaeology-and-dune-

geoarchaeology-of-lake-michigan

Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18.

University of Vermont, n.d. “Hypothetical Soil Horizons”. Accessed 12 December 2014. https://www.uvm.edu/place/analyze/soil_horizons.html

Yizhaq H, Ashkenazy Y,Tsoar H,. 2007. "Why do Active and Stabilized Dunes Coexist Under the Same Climatic Conditions?", Physical Review Letters, 98 (18).

Yizhaq H, Ashkenazy Y,Tsoar H,. 2009. “Sand Dune Dynamic and Climate Change: A Modeling Approach”, Journal of Geophysical Research, 114.

Appendix

Figure 1. Lake Michigan and Huron lake levels.

Image modified from Lovis et al. 2012 and Carlton College (SERC 2012)

Figure 2. Example of a soil profile.

Image modified from “Hypothetical Soil Horizons” (University of Vermont n.d.)

0 1 2 3 4 5 6 7 8 9 100.000

500.000

1000.000

1500.000

2000.000

2500.000

f(x) = 2204.98003272889 exp( − 0.0662733918906153 x )R² = 0.52444691614308

Iron

Relative Age

Conc

entra

tion

(ppm

)

Figure 3a. Element depletion of iron displaying significance in relation to the soil horizon relative age structure.

Figure 3b. Comparison of Figure 3a to Lichter’s data.

p= 0.014

0 1 2 3 4 5 6 7 8 9 100.000

50.000

100.000

150.000

200.000

250.000

300.000

f(x) = 183.875791884016 exp( − 0.112089114108591 x )R² = 0.490447718277681

Potassium

Relative Age

Conc

entra

tion

(ppm

)

Figure 4a. Elemental depletion of potassium displaying significance in relation to the soil horizon relative age structure.

Figure 4b. Comparison of Figure 4a with Lichter’s data. The box represents the range that the data fits within.

p= 0.018

0 1 2 3 4 5 6 7 8 9 100.000

50.000

100.000

150.000

200.000

250.000

f(x) = 118.156788051876 exp( − 0.151174989481577 x )R² = 0.391510097169674

Phosphorous

Relative Age

Conc

entra

tion (

ppm)

Figure 5a. The negative elemental depletion of phosphorous is significantly significant in relation to the soil horizon age structure.

Figure 5b. Age range that the data from Figure 5a. fits within when compared to Lichter.

p= 0.035

0 1 2 3 4 5 6 7 8 9 100.000

10.000

20.000

30.000

40.000

50.000

60.000

f(x) = 40.691858227085 exp( − 0.14745355782705 x )R² = 0.400245053045672

Zinc

Relative Age

Conc

entra

tion (

ppm)

Figure 6a. Zinc displays a significantly significant relationship between the soil horizon age structure and the concentration.

Figure 6b. Age range according to the shape of the line between Figure 6a and Lichter’s data.

p= 0.034

Figure 7. Image of a pit on GB. Taken 7 June 2014 by author.

Figure 8. Image of a pit on GC. Taken 7 June 2014 by author.

Figure 9. Image of a pit on GD. Taken 7 June 2014 by author.

Figure 10. Image of a pit on GE. Taken 8 June 2014 by author.

Figure 11. Image of a pit on GF. Taken 8 June 2014 by author.

Figure 12. Image of a pit on GG. Taken 8 June 2014 by author.

Figure13. Image of a pit on ED. Taken 9 June 2014 by author.

Figure 14. Image of a pit on EE. Taken 9 June 2014 by author.

Table 1. The elements highlighted in green correspond to those analyzed in Lichter (1998) and the data highlighted in yellow is below the detection limit and not used in this study.

ElementMethod Blank Reagent Blank Beach EDC D EDC E GPDC C GPDC D GPDC B GPDC F1 GPDC F2 GPDC G GPDC GE

Al 396.153 20.637 7.087 384.269 992.635 1505.801 707.095 444.149 961.198 453.618 619.477 500.624 691.360B 249.677 4.398 3.763 2.480 4.204 5.129 -0.565 2.949 9.200 0.252 4.788 5.463 9.680

Ba 233.527 3.601 0.544 1.453 5.374 15.419 2.335 -0.194 6.237 1.830 4.135 11.378 7.578Ca 317.933 91.102 75.585 4625.878 1322.149 4023.691 764.800 302.280 514.912 231.237 143.584 632.358 172.922Cd 228.802 0.203 0.301 0.514 0.145 0.841 0.093 1.014 0.166 0.296 0.145 0.067 0.170Co 228.616 0.021 -0.013 0.361 0.572 0.816 0.724 0.405 0.562 0.227 0.338 0.396 0.307Cr 267.716 0.960 0.736 1.544 2.335 3.183 3.140 1.876 9.138 1.830 2.386 1.771 2.923Cu 327.393 6.874 14.909 11.997 6.618 10.993 4.587 8.728 9.022 8.725 -0.511 -0.456 1.063Fe 238.204 9.507 8.354 851.847 1787.041 1967.179 2144.253 1546.948 1846.024 1160.960 1816.033 1324.468 1038.711

K 766.490 27.219 23.654 90.444 177.782 264.219 89.834 77.684 106.734 82.907 71.899 94.141 78.908Mg 285.213 8.668 3.825 1803.525 329.741 591.871 305.242 99.854 159.348 115.302 84.239 99.847 91.530Mn 257.610 0.203 0.133 13.926 39.780 104.179 48.641 15.819 20.719 12.065 20.615 173.871 10.226Mo 202.031 0.015 -0.020 0.308 0.335 0.590 0.254 0.220 2.453 0.164 0.560 0.233 0.895Na 589.592 112.193 95.739 80.263 213.002 112.681 179.696 89.327 26.943 56.084 173.180 46.798 351.391Ni 231.604 6.314 0.908 0.504 -1.519 -1.521 0.068 -3.929 1.745 2.240 -4.117 -1.973 -3.542P 213.617 0.686 -1.162 29.046 103.938 205.437 59.572 29.991 61.877 26.369 36.743 64.878 33.597

Pb 220.353 1.068 0.569 1.330 4.693 8.002 4.599 2.640 10.802 3.057 6.949 4.930 7.073Si 251.611 34.244 7.908 140.549 8.367 27.509 58.915 187.754 22.324 78.747 -10.020 -19.703 4.830Sr 421.552 0.157 0.086 3.191 3.096 5.536 3.505 1.474 2.890 1.207 1.684 2.573 2.132Zn 206.200 23.911 16.632 29.944 19.857 56.217 36.107 27.889 12.379 20.982 6.852 11.083 18.115