(d) interpret Earth surface features using a variety of methods
such as satellite imagery, aerial photography, and topographic and
geologic maps using appropriate technologies (11) Solid Earth. The
student knows that the geosphere continuously changes over a range
of time scales involving dynamic and complex interactions among
Earth's subsystems. The student is expected to:
Slide 2
Satellite photography can be used to produce composite images
of an entire hemisphere or to map a small area of the Earth, such
as this photo of the countryside of Haskell County, Kansas, United
States. SATELLITE IMAGERY Mt. Cotopaxi Satellite imagery consists
of photographs of Earth made by means of artificial satellites.
Satellite images have many applications including meteorology,
geology, forestry, intelligence and warfare. Images can be in
visible colors and in other spectra, such as infrared. There are
also elevation maps, usually made by radar images. Interpretation
and analysis of satellite imagery is conducted using specialized
remote sensing applications. Some of the first image enhancement of
satellite photos was conducted by the U.S. Government and its
contractors. Satellite imagery is also used in seismology and
oceanography in deducing changes to land formation, water depth and
sea bed, by color caused by earthquakes, volcanoes, and tsunamis.
The transceiver, in turn, relays the message via a satellite data
link to a control centre onshore.
Slide 3
ARIEL PHOTOGRAPHY Aerial photography is the technique of
capturing photographs of the land from an elevated location. This
type of photography usually refers to photographs which are taken
when the camera is not supported by a ground-based structure. The
camera in aerial photography may be hand held or mounted, and
photographs may be taken by a photographer, triggered remotely, or
triggered automatically. Aerial photography can produce some very
inspirational photographs that provide us a beautiful view of our
Earths surface from a perspective that we never see.
Slide 4
Unlike maps, which portray the physical and cultural landscape
with generalized symbols and colors, aerial photography reveals the
terrain as it exists in nature. All buildings, bridges, roads,
urban and rural areas, and other man-made features are depicted as
they were at the time of photography. Physical features, such as
vegetation type and distribution, river widths and courses,
shorelines, landslide areas, etc. are shown with detail that no map
can depict. Aerial photography is extremely useful both for site
evaluation and for regional analysis, as well as for historical
perspectives. It is used by engineers, architects, city and
regional planners, geographers, geologists and historians.
Slide 5
How can we use infrared light in satellite imaging? Describe
passive vs. active satellite sensing. Aerial photography can be
accomplished both by an actual photographer, or _____________,
using robotics. What are two positives of using aerial photography
over some other surface interpretation technique?
Slide 6
A topographic map, also known as a topo map, is a map which
shows changes in elevation by using contour lines. Contour lines
are imaginary lines that join points of equal elevation on the
surface of the land above or below a reference surface such as
average sea level. Contour lines make it possible to show the
height of mountains, depth of the ocean bottom, (on a special topo
map known as a bathymetric map) and steepness of slopes on a topo
map. To visualize what a contour line represents, picture a
mountain (or any other topographic feature) and imagine slicing
through it with a perfectly flat, horizontal piece of glass.
TOPOGRAPHIC MAPS
Slide 7
The contour interval is the difference in elevation between two
adjacent contour lines on a topo map. You can determine the contour
interval by counting the number of contours between labeled index
contours and then by using this formula: For example, on the map
shown here, you can see that there are 15 contour lines between the
2400 index contour and the 1800 index contour. So the contour
interval is calculated as follows: Contour Interval: 40 ft.
Slide 8
Close line =Steep Slope The steepest slopes on the map can be
seen by looking for lines that are very close together. Since each
line represents a change in elevation of a set amount (20 meters in
this example), lines that are close together indicate steep
gradients. The area circled in red is very steep, because it has
many lines crowded close together. Contour lines bend upstream when
crossing a river Since contour lines must remain at the same
elevation, they must bend when they cross riverbeds. A riverbed
drops downward, so the contour line must bend uphill to stay at the
same elevation. The highlighted lines show that the direction of
the Mill River must be northeast. Highest possible elevation of a
hill The highest elevation of a hill can be calculated by finding
the last (highest) contour line on that hill, and then figuring out
the next line that would be drawn. The highest possible elevation
of the hill is just below the value of that next line. The highest
possible elevation of the hill indicated by the arrow is 239
meters. The last line indicated on the map is 220 meters. The next
line would be 240 meters (remember that the contour interval is 20
meters). Since there is no 240 meter line, the hill cannot be
higher than 239 meters! Depressions are shown by small marks
pointing inward off the contour line The arrow is pointing to a
depression, or hole. The contour line with the marks, or hatchers,
has the same elevation as the line before it. In this case the
hatchered line has a value of 140 meters, and the depression must
be less than 140 meters. One of the most important sources of
information on a topographic map is the date of revision. Although
large scale topographic features (such as mountains) take millions
of years to be formed and eroded, other features, such as volcanoes
and river channels, may change on a much more rapid scale. volcanic
eruptions, flooding, landslides may alter topography significantly,
roads are added or go out of use, etc. Present Day
Slide 9
GEOLOGIC MAPS Geologic maps, like all maps, are designed to
show where things are. Unlike the maps we are used to which show
the distribution of roads or rivers or county boundaries, a
geologic map shows the distribution of geologic features, including
different kinds of rocks and faults. A geologic map is usually
printed on top of a regular map (called a base map) to help you
locate your location on the map. The base map is printed with light
colors, so it doesnt interfere with seeing the geologic features on
the map. The geology is represented by colors, lines, and special
symbols unique to geologic maps. Understanding these features will
allow you to understand much of the geology shown in almost any
standard geologic map. The most striking features of geologic maps
are its colors. Each color represents a different geologic unit. A
geologic unit is a volume of a certain kind of rock of a given age
range. So a sandstone of one age might be colored bright orange,
while a sandstone of a different age might be colored pale
brown.
Slide 10
Although the geology of every area is different, all geologic
maps have several features in common: colored areas and letter
symbols to represent the kind of rock unit at the surface in any
given area, and lines to show the type and location of contacts and
faults.
Slide 11
The geology of an area has a profound effect on many things,
from the likelihood of landslides, to the availability of
groundwater in wells, from the amount of shaking suffered in an
earthquake, to the presence of desirable minerals, from the way the
landscape is shaped to the kinds of plants that grow best there.
Understanding the earth underneath is the first step in
understanding the world around us. So whats the geology like in
your neighborhood? Holocene Period:Qal - Quaternary alluvium Qu -
Quaternary undivided Pleistocene Period:Qt - Quaternary terrace
deposits Cretaceous Period:Kau - Austin Chalk Kef - Eagle Ford Kwb
- Woodbine Kgm - Mainstreet & Grayson (undivided on map) Kpd -
Denton, Weno & Pawpaw Kpp - Pawpaw Kfd - Duck Creek & Fort
Worth (undivided on map) Kfw - Fort Worth Kki - Kiamichi Kgw -
Walnut & Goodland (undivided on map) Kpa - Paluxy sand
Slide 12
___________ on topographic maps are lines that join points of
equal elevation. One contour line is at 4,000 meters, and another,
higher up the mountain, is at 5,600 meters. There are 8 contours
crossed between the two. What is the contour interval? On a contour
map, the ___________ the lines are together, the _____________ the
slope. Calculate the contour interval on this map, in meters, and
determine the highest possible elevation of hill C. How are
depressions depicted on a contour map?
Slide 13
Why is the revision date on a topographic map of an area
depicting rivers and volcanoes more important than on topographic
maps showing other areas? What feature makes it easier to interpret
your location on a geologic map? Describe the geological foundation
of our area, and determine within which geologic period it was
laid.