GEOL1010
Hour Exam 2
28 Feb., 2005
1. Soils typical of regions with low rain fall and characterized by deposition of calcite due to a net evaporation of
water are known as:
a)pedalfers
b) pedocals
c) laterites
d) bauxites
e)evaporites.
2. The unconsolidated deposit of broken rock material on the surface of a planet is known as a:
a)pedalfer
b) pedocal
c) laterite
d) regolith
e)evaporites.
3. Soils of tropical rain forests commonly deep red in color and containing oxides and hydroxides of iron and
aluminum are known as:
a)pedalfers
b) pedocals
c) laterites
d) bauxites
e)evaporites
4. The processes of oxidation, hydration, and biological activity act to break down rocks at the Earth's surface.
Together, these processes constitute:
a) acid rain
b)mechanical weathering c) chemical weathering d)mass wasting e)metasomatism.
5. Chemical weathering is most rapid which type of climate:
a) cold and wet b) cool and wet c) cool and dry d) warm and wet
e) warm and dry
6. The yellow rust stain seen on stream boulders in some areas of Colorado are an indication of
a) acid mine drainage
b)mass wasting
c)lead contamination
d) mechanical weathering
e)acid rain.
7. Which of the following sequences of rock names has the correct arrangement in order of decreasing particle
diameters?
a) Conglomerate, shale, sandstone
b) Shale, siltstone, sandstone
c) Breccia, shale, sandstone, siltstone
d) Conglomerate, sandstone, siltstone, shale
e) Shale, sandstone, conglomerate
8. The following products all result from chemical weathering EXCEPT
a) Iron hydroxide b) CaCO3 in solution
c) clays
d) feldspar
e) sulfuric acid
9. A well-sorted, fine-grained quartz sandstone exhibiting large and extensive cross-bedding was probably
deposited in a:
a) alluvial fan
b) lagoon
c) abyssal plain d) desert
e) shallow sea.
10. In any sequence of sedimentary rocks, the beds are presumed to have been deposited in sequence with the
oldest on the bottom and the youngest on top. This is the principal of:
a)superposition b) cross-cutting c)physical continuity
d)original horizontality
e)mass wasting
11. A sedimentary rock composed of angular sand-, pebble-, and cobble-sized particles is a:
a) sandstone
b) breccia
c) conglomerate d)cobblestone
e)shale
12. The most abundant mineral in most eolian sandstone is:
a) calcite
b)clay
c) quartz
d) gypsum
e)feldspar
13. Which of the following minerals would not occur in an evaporite?
a) halite
b) gyspum
c) calcite
d) sylvite
e) zircon.
14. The coast of SE Alaska is marked by high mountains, volcanic rocks, fast streams, cool temperatures, and
high rain and snow falls. The sediments would not have time to completely weather chemically in such an
environment. The rivers deposit sand at the coastline. What kind of sand would you expect in this environment?
a) Arkosic (feldspathic) b) carbonate
c) conglomerate d) gypsum
e) eolian
15. Most of the gold and silver deposits here in Boulder County are the result of hot, aqueous solutions
emanating from granitic plutons that have intruded the Precambrian gneisses during the Tertiary (30 - 50 million
years ago). The process of hydrothermal alteration has weathered or hydrated the rock and deposited veins that
contain quartz, pyrite, native gold, gold tellurides, and silver sulfide minerals. The general term for this process
of ore formation by chemical exchange with fluids is:
a) migmatitization
b) foliation
c) zeolitic alteration
d) metasomatism e) polymorphism.
16. What is the distinguishing characteristic used to define the terms gravel, sand, silt, and clay:
a) mineralogy
b) rock-type
c) location
d) particle size e) particle shape.
17. A conglomerate formation contains cobbles of andesite (intermediate volcanic rock). The andesite was dated
radiometrically at 78 million years. Based on this date, we can infer the conglomerate layer to be:
a) more than 78 million years old
b) 78 million years old
c) less than 78 million years old
d) nearly 7000 years old
e) no inference is possible
18. The solid-state transformation of pre-existing rock into texturally or mineralogically distinct new rock is
known as:
a) sedimentation b) mass wasting c)lithification
d)metamorphism
e)metasomatism
19. The high-grade metamorphic equivalent of a limestone is a:
a) metaquartzite
b)eclogite
c) migmatite
d) slate
e)marble
20. Every mineral or mineral assemblage has a range of temperatures and pressures at which it is the most stable
configuration of the elements present. With increasing pressure such mineral assemblages typically become:
a)cooler
b) coarser
c) finer-grained
d) more dense
e)less dense.
21. The metamorphic facies characteristic of high-pressure, low-temperature rocks from a subduction zone is:
a) hornfels
b) granulite
c) zeolite
d) blueschist
e)greenschist
22. Land mammals and flowering plants proliferated during the:
a)Proterozoic
b) Cambrian
c)Mississippian d)Tertiary
e)Pleistocene
23. The Era of the dinosaurs is subdivided into the Triassic, Jurassic, and Cretaceous Periods. This Era is the:
a) Pre-Cambrian b) Paleozoic
c) Mesozoic
d) Cenozoic
e)Quaternary
24. Which of the following radioactive isotopes is formed in the atmosphere by cosmic ray bombardment:
a) 14C
b) 40K
c) 87Rb
d) 238U
e) 235U
25. If the amount of a radioactive element is 1/4 the amount originally present, how many half-lives have gone
by?
a) 1
b) 2
c) 3
d) 4
e) 3/4
26. An electron that escapes from a decaying radioactive isotope is called a:
a) Alpha particle
b)beta particle c) gamma photon
d) meson
e) X-ray
27. Any material that undergoes continuous plastic deformation is said to be:
a) anisotropic
b) brittle
c) sectile
d) ductile
e) elastic.
28. Deformation that is not recovered (permanent) on release on an applied force is said to be:
a) isostatic
b) shear
c) compressional
d) plastic
e) elastic.
29. The compass direction of the intersection of any tilted planar feature (such as bedding) with the horizontal is
the:
a) inclination
b) strike
c) declination
d) dip
e) elevation.
Questions 30-33 pertain to the designated faults in the diagram below.
30.
30. This type of fault is a:
a) reverse fault b) thrust fault
31.
32.
c) normal fault d) strike-slip fault
e) not my fault
31. This type of fault is a:
a) reverse fault b) thrust fault
c) normal fault
d) strike-slip fault
e) not my fault
32. This type of fault is a:
a) reverse fault b) thrust fault
c) normal fault
d) strike-slip fault
e) not my fault
Questions 33-35 pertain to the designated region in the diagram below.
33.
33. This type of fold is a(n)
a) anticline
b) syncline
34.
35.
c) monocline
d) basin
e) horst.
34. This type of fold is a(n):
a) anticline
b) syncline
c) monocline
d) basin
e) horst
35. This type of fold is a(n):
a) anticline
b) syncline
c) monocline
d) basin
e) horst
36. Extensive reverse and thrust faulting in an area is an indication of regional:
a) tectonic compression b) tectonic extension
c) metamorphism d) tectonic shear e) tectonic uplift.
37. At the San Andreas Fault in California, the Pacific Plate has moved to the north relative to the North
American Plate. This is an example of a:
a) dip-slip fault b) left-lateral strike slip fault
c) right-lateral strike-slip fault
d) thrust fault
e) reverse fault.
38. The imperceptibly slow movement of unconsolidated soils downslope (commonly indicated by curving tree
trunks and non-vertical poles, stakes and grave markers) is known as:
a) slump
b) creep
c) landslide
d) debris flow
e) talus slope.
39. A movement of a coherent mass of rock and soil a short distance typically along a curved lower surface (such
as happened at the intersection of highway 93 and U.S. 6 in Golden) is known as a
a) slump
b) slip
c) landslide
d) debris flow
e) talus slope.
40. The air-fluidized, high-velocity descent of a mass of debris and/or snow and ice a is known as a(n)
a) slump
b) slip
c) landslide
d) debris flow
e) avalanche.
Essay (write your answer on the scan-sheet).
In the diagram below a river canyon cuts through a sequence of flat-lying sediments, i-k, and
into a sequence of tilted sedimentary layers a-h, below which there are undifferentiated preCambrian metamorphosed sediments. There is a basaltic dike that cuts the metamorphic rocks
and the tilted sediments. Give a reasonable sequence of events that could have given rise to
these rocks
The sedimentary layers at the bottom were deposited and then deeply buried and metamorphosed.
Uplift and erosion to form a planar surface
Subsidence and deposition of sedimentary layers a-h.
Intrusion of basaltic dike
Uplift, tilting and erosion.
Deposition of sedimentary layers i-k.
Uplift and erosion of river valley