QUIZ # 8
Core Geology 3.32
1. When all the grains in a rock are roughly the same size, the rock is said to be _______.
A) well rounded
B) well sorted
C) spherical
D) angular
E) clastic
2. The group of processes that transform sediments into rock is known as _______.
A) compaction
B) transportation
C) diagenesis
D) oxidation
E) lithification
3. In the figure below, _______ are formed in wet and dry environments.
A)
B)
C)
D)
E)
ripple marks
mud cracks
footprints
cross beds
banded iron formation
4. _______ is the reduction of pore space in sediment as a result of the weight of the
overlying sediments.
A) evaporation
B) compaction
C) cementation
D) lithification
E) accretion
5. Glacial till is an example of a deposit that is _______.
A) well sorted
B) poorly sorted
C) well rounded
D) moderately rounded
E) spherical
6. A deposit with large clasts at the base that become finer upwards is known as a
_______.
A) ripple marks
B) mudcracks
C) oxidation
D) graded bed
E) calcareous ooze
7. Seasonal lakes, or _______, are common in arid areas.
A) alluvial fans
B) evaporites
C) playas
D) loess
E) banded iron formations
True/False
8. Mudcracks are sedimentary structures that are formed in wet/dry environments. TRUE
9. A semi-enclosed body of coastal water where fresh water mixes with marine water is
known as a delta. FALSE
10. The figure below shows a sedimentary structure that is formed by wind. FALSE
11. Some clastic sediments can be volcanic in origin. TRUE
Fill-In-The-Blank
12. _______ is the process in which substances dissolved in pore water are precipitated
out and join grains together. CEMENTATION
13. Most of the sediment on land is transported by _______. WATER/RIVERS
14. Seasonal lakes that form in arid areas are known as _______. PLAYAS
15. ______ processes are those referring to the wind. EOLIAN
Sort Essay
16. Explain the differences between sorting and roundness.
Sorting refers to the range of sediment grain sizes in a rock. Well sorted means the grain
sizes in the rock are all the same, whereas poorly sorted means there is a wide range of
sizes represented. Roundness refers to how close the grains are to being perfectly
spherical. The range of roundness is from angular to round.
17. Explain the difference between biogenic and chemical sediments.
Biogenic sediments are composed of plant and animal remains. Rocks formed from these
materials include coal and fossiliferous limestone. Chemical sediments form from the
precipitation of minerals dissolved in a lake, stream, or the ocean.
18. Please discuss the sediments sizes and the clastic rocks they form when lithified.
The four sediment sizes discussed in the chapter are gravel, sand, silt, and clay. These
four sediment sizes also can provide inferences on the energy of transport and distance
from the source. When lithified, the sediments form conglomerate, sandstone, siltstone,
and shale, respectively.
19. Discuss the similarities and differences between calcareous and siliceous ooze.
Calcareous and siliceous oozes are biogenic sediments that form on the sea floor from
small organisms. Calcareous oozes form when small, calcareous marine organisms die,
fall to the sea floor, and decompose. Siliceous oozes form when small, siliceous marine
organisms die, fall to the sea floor, and decompose.
20. Explain the difference between a material that is poorly sorted and a material that is
well sorted.
Poorly sorted materials have a wide range of grain sizes represented. A great example of
a poorly sorted material is glacial till. Well sorted material has only one grain size
represented. A great example of a well sorted material is quartz sand.
21. Explain the difference between a delta and an estuary.
Although both form in coastal environments, there are some differences. A delta is a
sedimentary deposit, usually in the shape of a triangle that forms when a stream enters a
standing body of water. An estuary is a semi-enclosed body of coastal water in which
fresh water mixes with sea water.
22. Explain how sedimentary facies can be useful to a geologist.
Sedimentary facies are the changes in the characteristics in sediment from one area to
another. Geologists can observe these changes and build a framework showing how the
facies change can from one area to another. For example, if coral fossils or reefs are
present, one can infer that the area was deposited on a carbonate shelf. Once the facies
are analyzed, the geologist can construct a geologic history of an area with respect to sea
level, climate, and paleotectonics through time.