Ch 4 - Physical Properties: Glass and Soil Physical and chemical properties. Physical and chemical properties. Metric and British systems. Metric and British

Ch 4 - Physical Ch 4 - Physical Properties:Properties:

Glass and SoilGlass and Soil Physical and chemical properties.Physical and chemical properties. Metric and British systems.Metric and British systems. Celsius (Centigrade) vs Fahrenheit.Celsius (Centigrade) vs Fahrenheit. Mass vs Weight.Mass vs Weight. DensityDensity Refractive IndexRefractive Index Crystalline vs Amorphous solids.Crystalline vs Amorphous solids. Double refraction and Double refraction and

birefringence.birefringence.

Dispersion of light through a prism.Dispersion of light through a prism. Flotation and immersion methods Flotation and immersion methods

for comparing glass specimens.for comparing glass specimens. Examining glass fractures to Examining glass fractures to

determine the direction of impact determine the direction of impact from a projectile.from a projectile.

Proper collection of glass evidence.Proper collection of glass evidence. Forensic properties of soil.Forensic properties of soil. Density-gradient tube technique.Density-gradient tube technique. Proper collection of soil evidence.Proper collection of soil evidence. http://http://www.fbi.gov/hq/lab/handbook/examglas.htmwww.fbi.gov/hq/lab/handbook/examglas.htm http://http://www.fbi.gov/hq/lab/handbook/examsoil.htmwww.fbi.gov/hq/lab/handbook/examsoil.htm

Physical property: Physical property: describes the describes the behavior of a substance without behavior of a substance without having to alter the substance’s having to alter the substance’s composition through a chemical composition through a chemical reactionreaction

Chemical property: Chemical property: describes the describes the behavior of a substance when it behavior of a substance when it reacts or combines with another reacts or combines with another substancesubstance

Fahrenheit scale: Fahrenheit scale: the temperature scale the temperature scale using the melting point of ice as 32using the melting point of ice as 3200 and and the boiling point of water as 212the boiling point of water as 21200, with 180 , with 180 equal divisions or degrees between them.equal divisions or degrees between them.

Celsius scale: Celsius scale: the temperature scale the temperature scale using the melting point of ice as 0using the melting point of ice as 000 and the and the boiling point of water as 100boiling point of water as 10000, with 100 , with 100 equal divisions or degrees betweenequal divisions or degrees between

Weight: Weight: a property of matter that a property of matter that depends on the mass of a substance and depends on the mass of a substance and the effects of gravity on that massthe effects of gravity on that mass

Mass: Mass: a constant property of matter that a constant property of matter that reflects the amount of material presentreflects the amount of material present

Density: Density: a physical property of matter a physical property of matter that is equivalent to the mass-per-unit that is equivalent to the mass-per-unit volume of a substancevolume of a substance

Refraction: Refraction: the bending of a light wave the bending of a light wave as it passes from one medium to anotheras it passes from one medium to another

Refractive index: Refractive index: the ratio of the the ratio of the speed of light in a vacuum to its speed in speed of light in a vacuum to its speed in a given substancea given substance

Crystalline solid: Crystalline solid: a solid in which the a solid in which the constituent atoms have a regular constituent atoms have a regular arrangementarrangement

Atom: Atom: the smallest unit of an element; the smallest unit of an element; not divisible by ordinary chemical means. not divisible by ordinary chemical means. Atoms are made up of electrons, Atoms are made up of electrons, protons, and neutrons plus other protons, and neutrons plus other subatomic particlessubatomic particles

Amorphous solid: Amorphous solid: a solid in which the a solid in which the constituent atoms or molecules are arranged constituent atoms or molecules are arranged in random or disordered positions. There is no in random or disordered positions. There is no regular order in amorphous solids.regular order in amorphous solids.

Birefringence: Birefringence: a difference in the two a difference in the two indices of refraction exhibited by most indices of refraction exhibited by most crystalline materialscrystalline materials

Dispersion: Dispersion: the separation of light into its the separation of light into its component wavelengthscomponent wavelengths

Tempered glass: Tempered glass: glass to which strength is glass to which strength is added by introducing stress through the rapid added by introducing stress through the rapid heating and cooling of the glass surfacesheating and cooling of the glass surfaces

Becke line: Becke line: a bright halo that is a bright halo that is observed near the border of a particle observed near the border of a particle immersed in a liquid of different immersed in a liquid of different refractive indexrefractive index

Radial fracture: Radial fracture: a crack in a glass that a crack in a glass that extends outward like the spoke of a extends outward like the spoke of a wheel from the point at which the glass wheel from the point at which the glass was struckwas struck

Concentric fracture: Concentric fracture: a crack in a a crack in a glass that forms a rough circle around glass that forms a rough circle around the point of impactthe point of impact

Mineral: Mineral: a naturally occurring a naturally occurring crystalline solidcrystalline solid

Density-gradient tube: Density-gradient tube: a glass a glass tube filled from bottom to top with tube filled from bottom to top with liquids of successively lighter liquids of successively lighter densities; used to determine the densities; used to determine the density destruction of soildensity destruction of soil

Ch. 4 – Glass and Soil Ch. 4 – Glass and Soil Properties of MatterProperties of Matter

The distinguishing characteristics of a The distinguishing characteristics of a substance used in its identification & substance used in its identification & descriptiondescription characteristics by which people are characteristics by which people are

recognizedrecognized hair color, tone of voice, walk, shape of nosehair color, tone of voice, walk, shape of nose

chemical substances are recognized by chemical substances are recognized by how they look & behavehow they look & behave

each chemical substance has a unique set of each chemical substance has a unique set of properties that distinguish it from all other properties that distinguish it from all other substancessubstances

Properties of MatterProperties of Matter

Chemical PropertiesChemical Properties a characteristic of a substance that a characteristic of a substance that

describes the way the substance describes the way the substance undergoes or resists change to form a undergoes or resists change to form a new substancenew substance

Physical PropertiesPhysical Properties a characteristic of a substance that can a characteristic of a substance that can

be observed without changing the be observed without changing the substance into another substancesubstance into another substance

Physical PropertiesPhysical Properties

Extensive PropertiesExtensive Properties depend on the amount of sampledepend on the amount of sample

volume, massvolume, mass

Intensive PropertiesIntensive Properties do not depend on the amount of sampledo not depend on the amount of sample

melting point, densitymelting point, density

DensityDensity

The ratio of the mass of an object to The ratio of the mass of an object to the volume occupied by that objectthe volume occupied by that object g/cmg/cm33 (solids); g/mL (liquids) (solids); g/mL (liquids)

d = m/Vd = m/V Densities of solids & liquids are Densities of solids & liquids are

often compared to the density of often compared to the density of waterwater sink or floatsink or float

Varies with temperatureVaries with temperature

RefractionRefraction

The bending that occurs when a The bending that occurs when a light wave passes at an angle from light wave passes at an angle from one medium to another (air to glass)one medium to another (air to glass)

bending occurs because the velocity of bending occurs because the velocity of the wave decreasesthe wave decreases

Refractive Index (NRefractive Index (NDD))

The ratio of the velocity of light in a The ratio of the velocity of light in a vacuum to the velocity of light in a vacuum to the velocity of light in a given mediumgiven medium NNDD (water) = 1.333 (water) = 1.333

light travels 1.333 time faster in vacuum light travels 1.333 time faster in vacuum than in waterthan in water

An intensive propertyAn intensive property Varies with temperature and the Varies with temperature and the

light frequencylight frequency

Double RefractionDouble Refraction

Crystals refract a beam of light into Crystals refract a beam of light into two different light-ray componentstwo different light-ray components extraordinary rayextraordinary ray

refracted (bent)refracted (bent) ordinary rayordinary ray

path unchangedpath unchanged Causes a double image to be seenCauses a double image to be seen No double refraction with isometric No double refraction with isometric

crystalscrystals

BirefringenceBirefringence

The difference between the two The difference between the two indices of refractionindices of refraction for calcite: 1.486 & 1.658for calcite: 1.486 & 1.658

birefringence for calcite is 0.172birefringence for calcite is 0.172

Use in identifying crystalsUse in identifying crystals

DispersionDispersion

Occurs when Occurs when an incident parallel beam of light to an incident parallel beam of light to

fans out according to the refractive fans out according to the refractive index of the glass for each of the index of the glass for each of the component wavelengths, or colors.component wavelengths, or colors.

GlassGlass

The BasicsThe Basics

What is Glass?What is Glass?

One of the oldest of all One of the oldest of all manufactured materialsmanufactured materials

A simple fusion of sand, soda & lime A simple fusion of sand, soda & lime (all opaque)(all opaque) produces a transparent “solid” when produces a transparent “solid” when

cooledcooled


An extended, 3D network of atoms An extended, 3D network of atoms which lacks the repeated, orderly which lacks the repeated, orderly arrangement typical of crystalline arrangement typical of crystalline materialsmaterials

The viscosity is such a high value The viscosity is such a high value that the amorphous material acts that the amorphous material acts like a solidlike a solid


glass is formed upon the cooling of a glass is formed upon the cooling of a molten liquid in such a manner that molten liquid in such a manner that the ordering of atoms into a the ordering of atoms into a crystalline formation is preventedcrystalline formation is prevented

materials which form glasses are materials which form glasses are relatively rarerelatively rare SiOSiO22 (silica) is the most common (silica) is the most common

exampleexample

Structure of GlassStructure of Glass


At ordinary temp. At ordinary temp. internal structure resembles a fluidinternal structure resembles a fluid

random molecular orientationrandom molecular orientation external structure displays the hardness external structure displays the hardness

& rigidity of of a solid& rigidity of of a solid Does not show a distinct melting Does not show a distinct melting

pointpoint on heating gradually softenson heating gradually softens on cooling gradually thickenson cooling gradually thickens


Common PropertiesCommon Properties hardhard perfectly elasticperfectly elastic brittle brittle non-conductors of electricitynon-conductors of electricity chemically stablechemically stable

Types of GlassTypes of Glass

Oxide GlassesOxide Glasses

Types of GlassesTypes of Glasses

~a thousand chemical formulations~a thousand chemical formulations each has its own combination of each has its own combination of

propertiesproperties more than 700 compositions in more than 700 compositions in

commercial usecommercial use Most common type encountered by Most common type encountered by

the forensic scientist is “flat” glassthe forensic scientist is “flat” glass glass used in windows & doorsglass used in windows & doors

ComponentsComponents FormersFormers

forms the glassy, non-crystalline structureforms the glassy, non-crystalline structure fluxesfluxes

improve melting properties but impart improve melting properties but impart low chemical resistancelow chemical resistance typically alkali or alkaline earth oxidestypically alkali or alkaline earth oxides

modifiers (stabilizers or modifiers (stabilizers or intermediates)intermediates) a material that improves stabilitya material that improves stability

typically oxides of Ca, Al, or Zntypically oxides of Ca, Al, or Zn

Common Glass Common Glass ComponentsComponents

FORMERS INTERMEDIATES MODIFIERS

SiO2 Al2O3 Na2O B2O3 PbO CaO GeO2 Sb2O3 K2O P2O5 ZnO MgO V2O5 TiO2 Li2O As2O3 BeO BaO

Soda-lime-glassSoda-lime-glass

Silica itself makes a glass (fused Silica itself makes a glass (fused silica)silica) high mp (3133 high mp (3133 ooF or 1723 F or 1723 ooC)C) high viscosity in liquid statehigh viscosity in liquid state difficult to melt & workdifficult to melt & work

NaNa22O (soda) lowers melting temp (A O (soda) lowers melting temp (A flux)flux) glass lacks durability (soluble in water)glass lacks durability (soluble in water)

CaO (lime) increases stabilityCaO (lime) increases stability

Borosilicate GlassBorosilicate Glass

Over 5% BOver 5% B22OO33 added to the silica added to the silica a heat resistant glass that expands only ~1/3 a heat resistant glass that expands only ~1/3

as much as silicate glassas much as silicate glass more resistant to breaking on rapid heating & more resistant to breaking on rapid heating &

coolingcooling PyrexPyrex

UsesUses laboratory ware & thermometerslaboratory ware & thermometers household glasswarehousehold glassware sealed-beam headlightssealed-beam headlights

Lead GlassesLead Glasses

Incorporates up to 80% PbOIncorporates up to 80% PbO Has high refractive index & high Has high refractive index & high

electrical resistivityelectrical resistivity Suitable for hand fabricationSuitable for hand fabrication Uses Uses

““crystal” tablewarecrystal” tableware costume jewelrycostume jewelry fine chandeliersfine chandeliers neon sign tubingneon sign tubing

Colored GlassesColored Glasses

Metallic oxides or sulfides added to Metallic oxides or sulfides added to soda-lime glasssoda-lime glass chromium oxide (green)chromium oxide (green) cobalt oxide (blue)cobalt oxide (blue) cadmium or selenium sulfide (red)cadmium or selenium sulfide (red)

Colloidal particles of iron & sulfur Colloidal particles of iron & sulfur produces the “carbon” brown beer produces the “carbon” brown beer bottlebottle

Decolorized GlassDecolorized Glass

General term for the soda-lime-glass General term for the soda-lime-glass marketed as “clear” for windowsmarketed as “clear” for windows

Color caused by impurities present in the Color caused by impurities present in the raw materials removed or maskedraw materials removed or masked destruction of carbonaceous matterdestruction of carbonaceous matter oxidation of Fe(II) (blue) to Fe(III) (yellow)oxidation of Fe(II) (blue) to Fe(III) (yellow)

NaNONaNO33, KNO, KNO3,, 3,, BaNOBaNO33

Most “clear” glass is not absolutely colorlessMost “clear” glass is not absolutely colorless observable by viewing on edgeobservable by viewing on edge

Light Sensitive Eyeglass Light Sensitive Eyeglass LensesLenses

Contain colloidal particles of silver Contain colloidal particles of silver halidehalide

Identified by exposure to uv lightIdentified by exposure to uv light

Glass ProductionGlass Production

Flat GlassFlat Glass until late 1950s produced by sheet * until late 1950s produced by sheet *

plate processesplate processes primarily produced by the float glass primarily produced by the float glass

process todayprocess today molten glass is “floated” over a bath of molten glass is “floated” over a bath of

molten timemolten time produces a distortion-free sheetproduces a distortion-free sheet

Glass Fracture Glass Fracture ExaminationExamination

Types of FracturesTypes of Fractures

Impact FracturesImpact Fractures

Impact causes a Impact causes a pane of glass to pane of glass to bulgebulge Side opposite the Side opposite the

impact will stretch impact will stretch more & rupture firstmore & rupture first

Radial cracks are Radial cracks are rapidly propagated rapidly propagated in short segments in short segments from the point of from the point of impactimpact


Ridges will be seen as irregularities on Ridges will be seen as irregularities on the broken edge of a radial crackthe broken edge of a radial crack


If the pane is held firmly on both sidesIf the pane is held firmly on both sides a circular pattern of cracks (concentric) will a circular pattern of cracks (concentric) will

form around point of impactform around point of impact

Forensic ExaminationForensic Examination

Ridges on radial cracks can be used Ridges on radial cracks can be used to determine on which side of pane to determine on which side of pane impact occurredimpact occurred

To perform examinationTo perform examination identify one or more pieces which have identify one or more pieces which have

cracks terminating at a point of impactcracks terminating at a point of impact fit these pieces onto one or more pieces fit these pieces onto one or more pieces

marked “inside” or “outside”marked “inside” or “outside”

Four R RuleFour R Rule

RRidges on idges on RRadial adial cracks are atcracks are at R Right ight angles to the angles to the RRear ear (side opposite the (side opposite the impact)impact)

Four R RuleFour R Rule

ExceptionsExceptions tempered glasstempered glass

““dices” without forming ridgesdices” without forming ridges very small windows held tightly in very small windows held tightly in

frameframe can’t bend or bulge appreciablycan’t bend or bulge appreciably

windows broken by heat or explosionwindows broken by heat or explosion no “point of impact”no “point of impact”

Heat FracturesHeat Fractures

typical heat crack is curvedtypical heat crack is curved has a smooth edge (“mirror edge”)has a smooth edge (“mirror edge”) no indication of point of impactno indication of point of impact

Fractures Caused by Fractures Caused by ProjectilesProjectiles

High-velocity projectilesHigh-velocity projectiles crater-like hole surrounded by a nearly crater-like hole surrounded by a nearly

symmetrical pattern of radial and symmetrical pattern of radial and concentric cracksconcentric cracks

the size of the hole & diameter of crater the size of the hole & diameter of crater are relatively independent of the size of are relatively independent of the size of the projectilethe projectile

Fractures Caused by Fractures Caused by ProjectilesProjectiles

Bullet AnalysisBullet Analysis If a window is broken by a

bullet, it is possible to determine the bullet's direction by noting the side of the cone-shaped hole left by the bullet. The small opening is on the entrance side and the large opening is on the exit side.

A determination of the sequence of bullet holes can be made by noting the radial fractures. Radial fractures caused by the passage of a bullet will stop at any pre-existing fracture.

Glass CuttersGlass Cutters

score the surface of glass by forcing score the surface of glass by forcing out tiny chips along a lineout tiny chips along a line

small chips will be missing on one small chips will be missing on one side of the pane along the breakside of the pane along the break

Cutter type can’t be accurately Cutter type can’t be accurately determineddetermined

Association to a particular cutter Association to a particular cutter possible only when glass chips are possible only when glass chips are deposited on a cutterdeposited on a cutter

Mechanical FitMechanical Fit

Examiner can determine that two or Examiner can determine that two or more pieces of glass were broken more pieces of glass were broken from the same pane or objectfrom the same pane or object

Because glass is amorphous, no two Because glass is amorphous, no two glass objects will break the same glass objects will break the same wayway

Figure 4-10 p. 98Saferstein

Comparing Glass Comparing Glass FragmentsFragments

Using Physical PropertiesUsing Physical Properties

Glass as Forensic Glass as Forensic EvidenceEvidence

Films of breaking glass have shown Films of breaking glass have shown that glass flies backward from all that glass flies backward from all parts of the window where cracks parts of the window where cracks appearappear not just from point of impactnot just from point of impact

Results in a shower of minute glass Results in a shower of minute glass particles onto the window breakerparticles onto the window breaker

Glass as Forensic Glass as Forensic EvidenceEvidence

Glass fragments recovered from Glass fragments recovered from clothingclothing number & distribution are importantnumber & distribution are important

a piece of glass embedded in a shoe has low a piece of glass embedded in a shoe has low probative valueprobative value

many small fragments from a shirt or many small fragments from a shirt or sweater can be highly significantsweater can be highly significant

Glass must be classifiedGlass must be classified window glass vs broken bottle glasswindow glass vs broken bottle glass

Individualization may be possibleIndividualization may be possible

Classification TestsClassification Tests

Physical properties can be used to Physical properties can be used to place glass into a classplace glass into a class DensityDensity Refractive Index (RI)Refractive Index (RI)

Individualization can’t be Individualization can’t be determined from these properties determined from these properties alonealone

Can be used to evaluate the Can be used to evaluate the significance of a glass comparisonsignificance of a glass comparison

Flotation TestFlotation Test

Based on densityBased on density Glass is not perfectly homogeneousGlass is not perfectly homogeneous

test allows for small internal density test allows for small internal density variationsvariations

The control glass chip (known density)The control glass chip (known density) immersed in mixture of bromoform & immersed in mixture of bromoform &

bromobenzenebromobenzene composition of mixture altered until the composition of mixture altered until the

chip remains suspendedchip remains suspended

Flotation TestFlotation Test

The crime object (glass of unknown The crime object (glass of unknown density) immersed in liquid mixturedensity) immersed in liquid mixture remains suspendedremains suspended

liquid, control & unknown have same liquid, control & unknown have same densitydensity

sinkssinks unknown is more dense than controlunknown is more dense than control

different originsdifferent origins

Accurate density measurements can Accurate density measurements can be obtained with a Density Meterbe obtained with a Density Meter

Refractive Index By Refractive Index By ImmersionImmersion

Entails finding the temp at which a Entails finding the temp at which a glass particle & a liquid, into which glass particle & a liquid, into which the chip has been immersed, have the chip has been immersed, have identical refractive indicesidentical refractive indices refractive index of glass is relatively refractive index of glass is relatively

unaffected by changing tempunaffected by changing temp refractive index of liquid varies with refractive index of liquid varies with

temptemp dN/dT=-4 x 10dN/dT=-4 x 10-4-4//ooCC


Immerse glass in high boiling liquidImmerse glass in high boiling liquid Increase temp at rate of 0.2 Increase temp at rate of 0.2 ooC/minC/min At match point the refractive index of At match point the refractive index of

liquid & glass are the sameliquid & glass are the same Becke line disappearsBecke line disappears minimum contrast between glass & liquid minimum contrast between glass & liquid

If all glass fragments have similar If all glass fragments have similar match points, they have comparable match points, they have comparable RIRI

Figure 4-12 p. 101Saferstein


Internal RI variations may vary by Internal RI variations may vary by 0.00020.0002

Differences in RI must be greater Differences in RI must be greater than 0.0002 between suspect & than 0.0002 between suspect & crime glass to be significantcrime glass to be significant

The measurement of RI alone can be The measurement of RI alone can be of limited use for classification of limited use for classification because RI distributions of flat because RI distributions of flat glasses and container glasses glasses and container glasses overlapoverlap

Histogram = flat glassesCurve = container glasses

Other Classification Other Classification MethodsMethods

MicroscopyMicroscopy float glass is absolutely flatfloat glass is absolutely flat wine glasses are slightly curvedwine glasses are slightly curved bottles have microscopic defects from bottles have microscopic defects from

mouldmould FluorescenceFluorescence

when excited by uv radiation, many when excited by uv radiation, many glasses exhibit fluorescenceglasses exhibit fluorescence caused by heavy metals (including tin)caused by heavy metals (including tin)

FluorescenceFluorescence Can differentiate Can differentiate

between float and between float and non-float window non-float window glassglass

Can differentiate Can differentiate between different between different samples of float samples of float glass in some casesglass in some cases

(a) non-float glass or non-float side(b) float side Sample #1(c) float side Sample #2

Scanning Electron Scanning Electron MicrocopyMicrocopy

Can detect Can detect SiSi NaNa CaCa MgMg KK

very small samples very small samples can be analyzed can be analyzed (50 micrograms)(50 micrograms)

X-ray FluorescenceX-ray Fluorescence

Can detect major Can detect major elements in glass elements in glass samplessamples

sometimes detects sometimes detects minor & trace level minor & trace level componentscomponents

Elemental AnalysisElemental Analysis

Many of the trace elements enter the Many of the trace elements enter the glass via trace impurities in the raw glass via trace impurities in the raw materialsmaterials

Comparison of elemental analysis of crime Comparison of elemental analysis of crime glass & reference glassglass & reference glass if ranges of elements overlap for every if ranges of elements overlap for every

elementelement indistinguishableindistinguishable

if ranges of one or more elements are differentif ranges of one or more elements are different samples are distinguishablesamples are distinguishable

Red= flat blue= container black= tablewareRI=1.5177-1.5183

Soil AnalysisSoil Analysis

What Is Soil? What Is Soil? Mixture of organic and inorganic Mixture of organic and inorganic

materialmaterial May range from 100% inorganic May range from 100% inorganic

(sand) to nearly 100% organic (sand) to nearly 100% organic (peat)(peat)

Inorganic part is mineralsInorganic part is minerals Organic part is decayed plant and Organic part is decayed plant and

animal material and is sometimes animal material and is sometimes called humascalled humas

Soil AnalysisSoil Analysis"For example, observation shows me that you have been to the "For example, observation shows me that you have been to the

Wigmore Street Post-Office this morning, but deduction lets me Wigmore Street Post-Office this morning, but deduction lets me know that when there you dispatched a telegram."know that when there you dispatched a telegram."

"Right!" said I. "Right on both points! But I confess that I don't "Right!" said I. "Right on both points! But I confess that I don't see how you arrived at it. It was a sudden impulse upon my part, and see how you arrived at it. It was a sudden impulse upon my part, and I have mentioned it to no one."I have mentioned it to no one."

"It is simplicity itself," he remarked, chuckling at my "It is simplicity itself," he remarked, chuckling at my surprise--"so absurdly simple that an explanation is superfluous; and surprise--"so absurdly simple that an explanation is superfluous; and yet it may serve to define the limits of observation and of deduction. yet it may serve to define the limits of observation and of deduction. Observation tells me that you have a little reddish mould adhering to Observation tells me that you have a little reddish mould adhering to your instep. Just opposite the Wigmore Street Office they have taken your instep. Just opposite the Wigmore Street Office they have taken up the pavement and thrown up some earth, which lies in such a way up the pavement and thrown up some earth, which lies in such a way that it is difficult to avoid treading in it in entering. The earth is of that it is difficult to avoid treading in it in entering. The earth is of this peculiar reddish tint which is found, as far as I know, nowhere this peculiar reddish tint which is found, as far as I know, nowhere else in the neighbourhood. So much is observation. The rest is else in the neighbourhood. So much is observation. The rest is deduction." deduction."

(From (From The Sign of FourThe Sign of Four by Arthur Conan Doyle) by Arthur Conan Doyle)

Soil AnalysisSoil AnalysisForensic GeologyForensic Geology is the scientific application is the scientific application

of earth sciences to legal matters. of earth sciences to legal matters. Identifying, analyzing, and comparing earth Identifying, analyzing, and comparing earth

materials, such as soil, rocks, minerals, and materials, such as soil, rocks, minerals, and fossils found on or in a receptor (e.g., a suspect, fossils found on or in a receptor (e.g., a suspect, a vehicle or other medium of transfer, such as a vehicle or other medium of transfer, such as water) to possible source areas (e.g., a crime water) to possible source areas (e.g., a crime scene, an alibi location, and/or a point of scene, an alibi location, and/or a point of disposal/release). disposal/release).

Goal - Goal - establish the degree of probability that the material establish the degree of probability that the material

was or was not derived from a particular locationwas or was not derived from a particular location determine the time an incident occurred, the cause determine the time an incident occurred, the cause

of an incident and/or responsibility for an incident.of an incident and/or responsibility for an incident.


Bulk analysisBulk analysisDensity gradientDensity gradientParticle size distribution (sieving)Particle size distribution (sieving)Inorganic componentsInorganic componentsColor (dissolve in water)Color (dissolve in water)Petrography - mineral analysisPetrography - mineral analysisOrganic componentsOrganic componentsLiquid chromatographyLiquid chromatographyOxygen availabilityOxygen availabilityBacterial DNA?Bacterial DNA?

Soil AnalysisSoil AnalysisHit and Run: - Under-fender dirt/soil deposited at

impact with the victim was used to locate the car/driver; also, matching the grease on the victim with the grease under the car provided supporting evidence.

Rape: - Soil on clothing of a suspected rapist was used to place the suspect at the crime scene and to eliminate the suspect's alibi.

Murder: - Soil found on murder victims used to determine the location of homicides, especially when the murder occurs in one location and the body is then moved. Using water-current measurements, bodies/objects thrown into water can be located and where a discovered body/object originally entered the water determined.

Assault: - Identifying the type of rocks used as weapons led to the source of the rocks and helped locate suspects.

Soil AnalysisSoil AnalysisSoil provided strong evidence against a rape suspect when Soil provided strong evidence against a rape suspect when

comparison of soil samples on each knee of his pants matched the comparison of soil samples on each knee of his pants matched the soil types from the right and left knee impressions at the rape soil types from the right and left knee impressions at the rape scene. In other cases, analyses of soil on clothing have been scene. In other cases, analyses of soil on clothing have been used to support alibis and show no connection of the suspect to used to support alibis and show no connection of the suspect to the crime scene. the crime scene.

By identifying the nature and extent of groundwater By identifying the nature and extent of groundwater contamination, a forensic geologist determined the time a chemical contamination, a forensic geologist determined the time a chemical release contaminated water supplies. In another case, a similar release contaminated water supplies. In another case, a similar analysis showed that contamination in groundwater at a company analysis showed that contamination in groundwater at a company originated at another property and a different company was originated at another property and a different company was responsible for cleanup.responsible for cleanup.

By analyzing road maintenance records and techniques used By analyzing road maintenance records and techniques used to sample an unpaved road, a forensic geologist provided to sample an unpaved road, a forensic geologist provided evidence that eliminated the validity of the opposition's roadway evidence that eliminated the validity of the opposition's roadway data and skid testing in a motor vehicle accident case. Geologic data and skid testing in a motor vehicle accident case. Geologic analyses of roadways in other cases have shown that unpaved analyses of roadways in other cases have shown that unpaved roads were improperly constructed and/or improperly maintained.roads were improperly constructed and/or improperly maintained.


(1908) A man with a bad reputation was under investigation for the (1908) A man with a bad reputation was under investigation for the murder of Margaeth Filbert in Bavaria, Germany. Investigating mud on murder of Margaeth Filbert in Bavaria, Germany. Investigating mud on the suspect's shoes helped solve the case.the suspect's shoes helped solve the case.

The suspect's wife testified that she had cleaned her husband's The suspect's wife testified that she had cleaned her husband's shoes the day before the crime. Those shoes had three layers of soil shoes the day before the crime. Those shoes had three layers of soil adhering to the leather in front of the heel with the innermost layer as adhering to the leather in front of the heel with the innermost layer as the oldest. It contained goose droppings et al, matching samples from the oldest. It contained goose droppings et al, matching samples from the walk outside the suspect's home. The second layer contained red the walk outside the suspect's home. The second layer contained red sandstone fragments that compared with samples taken where Filbert's sandstone fragments that compared with samples taken where Filbert's body had been found. The last layer contained brick, coal dust, cement body had been found. The last layer contained brick, coal dust, cement and other materials that matched samples taken outside a castle and other materials that matched samples taken outside a castle where the suspect's gun and clothing had been found. where the suspect's gun and clothing had been found.

The suspect claimed he'd been walking in his fields the day of the The suspect claimed he'd been walking in his fields the day of the crime. The lie didn't stick. Those fields were underlain by porphyry crime. The lie didn't stick. Those fields were underlain by porphyry with milky quartz, and the soil had been wet that day. But they found with milky quartz, and the soil had been wet that day. But they found no such material on the suspect's shoes. no such material on the suspect's shoes.

Soil AnalysisSoil Analysis Soil is frequently found on clothing, shoes, or

tools and in the wheel wells of vehicles. Most soil analysis consists of comparing two

or more samples by their mineral content, color, and density. The presence of pesticides and herbicides have also been used in soil comparison.

Soil AnalysisSoil AnalysisTHE CAMARENA CASETHE CAMARENA CASE

In 1985, an agent with the U.S. Drug Enforcement Agency, In 1985, an agent with the U.S. Drug Enforcement Agency, Enrique Camarena Salazar, was kidnapped near Guadalajara. Enrique Camarena Salazar, was kidnapped near Guadalajara. The U.S. government demanded that the Mexican government The U.S. government demanded that the Mexican government and Mexican Federal Judicial Police (MFJP) find Camarena. and Mexican Federal Judicial Police (MFJP) find Camarena. Eventually the MFJP announced finding Camarena's body on the Eventually the MFJP announced finding Camarena's body on the El Mareno ranch in Michoacan State, the site of a shootout El Mareno ranch in Michoacan State, the site of a shootout between Mexican police and alleged drug dealers. between Mexican police and alleged drug dealers.

But an investigation by the FBI showed that Camarena's But an investigation by the FBI showed that Camarena's body had been buried elsewhere before arriving at the ranch. body had been buried elsewhere before arriving at the ranch. The clue was a specific tuffaceous rhyolite ash found in The clue was a specific tuffaceous rhyolite ash found in material adhering to Camarena's exhumed body. The ash material adhering to Camarena's exhumed body. The ash helped investigators find Camarena's original burial site - a helped investigators find Camarena's original burial site - a grave in a state park called Bosques de la Primavera, far from grave in a state park called Bosques de la Primavera, far from the ranch. The body had been removed from that site to the the ranch. The body had been removed from that site to the ranch, and the investigation helped reveal a cover-up by the ranch, and the investigation helped reveal a cover-up by the MFJP. MFJP.

Soil AnalysisSoil Analysis Microscopic fossils called Microscopic fossils called diatomsdiatoms were once very were once very

prominent on Earth, and collectively deposited to form prominent on Earth, and collectively deposited to form a sedimentary rock called diatomaceous earth. Some a sedimentary rock called diatomaceous earth. Some manufacturers use diatomaceous earth for insulating manufacturers use diatomaceous earth for insulating safes, that are used to store valuables. Burglary safes, that are used to store valuables. Burglary crimes have been solved by examining white specks crimes have been solved by examining white specks from suspects' hair and clothing to determine that the from suspects' hair and clothing to determine that the specks were actually diatoms that came from broken specks were actually diatoms that came from broken safes at crime scenes, and not dandruff as the safes at crime scenes, and not dandruff as the suspects had claimed.suspects had claimed.

Documents

Ch 4 - Physical Properties: Glass and Soil Physical and chemical properties. Physical and chemical properties. Metric and British systems. Metric and British