Formative Assessment #1: Unit 1 Module 2
PART 1
The first place to examine will require you to find 37º 20’ 02” N 100º 03’ 27” W, at
an eye altitude of 5,000 km. You might find it challenging to get the Google Earth
cursor exactly on these values but so long as you are close (within 1 to 2
degrees geographic location and 100-200 kilometers eye altitude you should be
fine).
If you have done everything correctly you should find yourself looking down onto
North America and located almost exactly overtop of the middle of the United
States.
Now answer these following questions:
1A. Describe the fundamental morphologic differences between the sub aerial
(above sea level) landforms of the western and eastern United States within 500
km of the land-water boundary? Hint: Is the topography the same for each side of
the United States within this 500 km zone? Explain the differences if there are
differences.
2A. Explain what large-scale process is likely contributing toward the differences
in topography that you notice. Hint: What are the tectonic differences between
each margin.
3A. If you were to place each coastal margin into the plate tectonic classification
scheme for coasts which categories would each margin fit into?
4A. The lighter shading of blue on the edge of the continents indicates the
shallow water continental shelves compared to the darker blue coloration beyond
the shelves that is used to show the deeper water of the center of the oceans.
What difference(s) do you notice between the North American continental shelf of
the western margin and the eastern margin?
5A. On the basis of the reading you have done for plate tectonic classification of
coasts provide some ideas as to why you think there are differences between the
western and eastern continental shelf? Hint: What processes can act to extend a
continental shelf seaward through time.
Part 2
The second place to examine will require you to find the geographic coordinate of
S 15º 00’ 00”, 25 º 03’ 27” E, at an eye altitude of 3,500 km. Again you might find
it challenging to get the Google Earth cursor exactly on these values but so long
as you are close (within 1 to 2 degrees geographic location and 100-200
kilometers eye altitude you should be fine).
If you have done everything correctly you should find yourself looking down onto
the southern part of the African continent, just north of the Tropic of Capricorn.
Now answer the following questions:
1B. What type of plate tectonic classification is most suitable for the eastern and
western margin of this part of Africa? Note that each margin faces a spreading
center.
2B. Using the measuring tool in Google Earth (measuring stick icon on the top
tool bar) measure the linear distance across the continental shelf on the western
margin (shelf is the light blue area adjacent to the land) at the latitude of the
Tropic of Capricorn. Assume that the seaward edge of the shelf here is at
approximately 13 º 00’ 00” E. Provide your answer in kilometers. Is the edge of
the shelf here very pronounced or appear to have a gradual gradient into the
deeper ocean. Note you will have to zoom in a bit to see the shelf and shelf edge
more clearly.
3B.Describe what happens to the continental shelf width to between the Tropic of
Capricorn and S 17º 00’ 00” along the eastern margin of southern Africa?
4B. What is one process that could explain the differences in the continental shelf
that you have observed between the two latitudes of the previous question?
5B. Move over to the western margin of southern Africa at the latitude of the
Tropic of Capricorn. Zoom into an eye altitude of 300 km and examine the shape
of the coastline and the land area along the coast between the Tropic of
Capricorn and S 24º 15’ 00”. What do you think is the dominant subaerial
environment within 50 km of the coastline? Consequently what type of sediment
do you think is most common along this section of the African coastline? Does
the configuration of the shoreline suggest that this is an erosional or depositional
coast?