GeoSci28 - 2 The diagram above shows a geologic...

2. The diagram above shows a geologic cross-section of some rocks, such as you might see in a
cliff. The tree is growing on top of the modern surface. Rock layers A, B, C, D, E, and F are
sedimentary; E contains mud cracks and fossil footprints as shown. G is igneous rock that
hardened from hot, melted rock. H, I and J are faults, and K and L are unconformities.
Sedimentary rocks are right-side-up unless there is some indication given to show something
else.
Referring to the rocks you see here ...... Which is the oldest sedimentary rock layer?
A. C
B. D
C. F
D. E
E. B

The package of sediments C, D, E, and F is upside-down, as shown by the footprints and mud
cracks, so C is the oldest one.
Points Earned: 0/1
Correct Answer: A
Your Response: D
3. The two pictures above, I and II, show fossils in rocks from the Grand Canyon. Each is
"typical"; the rocks near sample I contain fossils similar to those shown in sample I, and the
rocks near sample II contain fossils similar to those shown in sample II.
It is likely that:
Sample I is a wonderful shell hash, or coquina, from the Supai Rocks well up the side of the
Canyon, and contains shells from a great diversity of different creatures. Sample II includes
algal-mat deposits (stromatolites) from the Precambrian Chuar Group of the Grand Canyon

Supergroup, deep in the Canyon near the river, from a time when biology was not a whole lot
more diverse than algal mats.