Geology hw 6

Clay material formed from gabbro or diorite bedrock illustrate which kind of weathering? Chemical proactive syntropical mechanical

A

Flint, chert, and jasper are microcrystalline forms of __________. quartz; (SiO2) hematite (Fe2O3) halite (NaCl) calcite (CaCO3)

A

From the land surface downward to the unweathered bedrock, which of the following is the correct order of the different soil horizons? 0, A, E, B, C, bedrock A, B, C, D, E, bedrock E, A, B, C, 0, bedrock D, E, C, B, A, bedrock

A

Lateritic soils form under what climatic conditions? warm and moist as in a wet, tropical forest cool and relatively dry as in the northern Great Plains of the United States hot and dry as in the desert regions of North Africa and Arabia moist and temperate as in the northeastern United States

A

Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage). Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)? 5%; 75% 3.5%; 100% 65%; 10% 85%; 100%

A

Studies of deep-sea sediment cores have contributed greatly to scientific knowledge of __________. climatic changes during the last four million years how soft-bodied organisms are carbonized the origin of oscillation ripple marks in deep-sea muds the biological impacts of pollution on parts of the continental shelves

A

What is the main difference between a conglomerate and a sedimentary breccia? Breccia clasts are angular; conglomerate clasts are rounded. A breccia is well stratified; a conglomerate is poorly stratified. Breccia clasts are the size of baseballs; conglomerate clasts are larger. Breccia has a compacted, clay-rich matrix; conglomerate has no matrix.

A

Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks? clays carbonates quartz ferromagnesian minerals

A

Which of the following best describes the process of eluviation? removal of very fine-sized silt and clay particles from the A and E soil horizons buildup of calcite in the B horizon of pedocal soils removal of soluble chemical constituents from the A and B soil horizons feldspar decomposition and leaching of the soluble products from the C soil horizon

A

Which of the following is not a type of limestone? arkose coquina chalk travertine

A

Which of the following sedimentary features would typically be found in shales but not in sandstones? mud cracks cross stratification ripple marks bedding

A

Which of the following statements about laterites or tropical rainforests is true? Laterite soils readily compact and hardened when dried and exposed to sunlight. Rainforests regenerate quickly following clear cutting or clearing for agriculture. Laterite soils are very rich in nutrients required for vigorous plant growth. Laterites, with proper management, are very suitable for commercial agriculture.

A

Which one of the following statements concerning soil erosion is not true? Sheet erosion, rills, and gullies develop mainly during prolonged droughts. Soils form naturally by weathering; if protected from erosion, sound management can maintain or enhance their nutrient levels and textural characteristics. Rates of soil erosion exceed rates of soil formation in some parts of the world. Grasses and other vegetation, windbreaks, and contour cropping will help reduce losses of soil from cultivated lands.

A

Which type of sediment undergoes the most compaction as it lithifies to sedimentary rocks? marine mud desert dune sand reef limestone coarse gravel

A

Zircon and tourmaline are dense, highly insoluble, chemically stable, minor minerals of igneous and metamorphic rocks. In which sedimentary rock might you expect to find these minerals concentrated? sandstone lithified from quartz-rich beach sand limestone representing lithified coral-reef carbonates a thin, upper, mudstone portion of a thick graywacke bed with graded bedding evaporite deposits of gypsum and salt

A

_______ is the most common type of chemical sedimentary rock. Limestone Chert Phosphate rock Quartz sandstone

A

_________ is a form of calcium carbonate Travertine Chert Lignite Gypsum

A

A graywacke is __________. a limestone with abundant, sand-sized, quartz grains a sandstone with the sand grains embedded in a clay-rich matrix a dark-gray, calcite-rich mudstone or shale containing pyrite a dark, organic-rich, chemical sedimentary rock containing small crystals of halite

B

Detrital sedimentary rocks are classified (named) based on the __________. colors of the cementing minerals grain sizes of the detrital particles compositions of soluble minerals degree of compaction and lithification

B

Frost wedging is the major weathering process contributing to the formation of which regolith material? tropcial laterites talus slopes C soil horizontal mature pedalfers

B

Oolitic limestone is most likely to form in what type of depositional environment? quiet, muddy, lagoons and bays shallow, clear, marine waters with vigorous current activity deep, marine waters below most wave action acidic, organic-rich waters in freshwater swamps and bogs

B

Under similar warm, moist climatic conditions, why would basalt and gabbro generally have higher chemical weathering rates than rhyolite and granite? The quartz in the gabbro and basalt decomposes very quickly. The ferromagnesian minerals in the gabbro and basalt are subject to oxidation and chemical breakdown. The plagioclase feldspars in the granite and rhyolite decompose readily to clay minerals and iron oxides. The potassium feldspars and quartz in the rhyolite and granite are more susceptible to cracking by frost wedging.

B

What two, chemical constituents cannot form by chemical weathering of the feldspar minerals? soluble sodium and potassium bicarbonates insoluble iron oxides and soluble magnesium bicarbonates silica and insoluble clay minerals silica and soluble calcium bicarbonate

B

Which of the following best describes sets of fractures in relatively fresh bedrock, such as granite, that are roughly parallel to the land surface? thermal expansion cracks sheeting fractures hydrolytic failures columnar joints

B

Which of the following statements about acidic precipitation is likely to be false? Chemical weathering and deterioration of exposed rock and metal surfaces will accelerate if acidic precipitation increases. Lowered taxes and relaxed governmental regulations will result in more private and public sector spending to reduce emissions of acid-forming gases to the atmosphere. Fish and other aquatic species in acidified lakes will eventually die off and disappear due to the toxic effects of the acidic waters and increased levels of dissolved aluminum. Damage to trees and plants, especially to tender new growth, will intensify if acidic precipitation worsens.

B

Which term describes a soil formed by weathering of the underlying bedrock? transformational residual relict transported

B

Assume that water filling a crack in a rock undergoes cycles of freezing and melting. Which of the following statement is true? Water expands as it melts, causing the crack walls to be pushed apart. Water shrinks as it freezes, causing the crack walls to be drawn closer together. Water expands as it freezes, causing the crack walls to be pushed apart. Water shrinks as it melts, causing the crack walls to be pulled closer together.

C

Clay minerals silica (Si02), and sdissolved potassium bicarbonate in the soil water are products of which process? chemical weathering of olivine and plagioclase feldspar mechanical weathering of granite and rhyolite chemical weathering of orthoclase feldspar differential mechanical weathering of micas

C

Compaction is a very important part of the lithification process for which of the following sediments? gravel sand mud cobble

C

Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern. lithification cementation weathering compaction

C

In the Rocky Mountain region of the United States, north-facing slopes (downhill direction is toward the north) are typically more moist and heavily forested than south-facing slopes. Why? North-facing slopes receive more sunlight in the summer; snow melts faster and more soil moisture is available for the trees. South-facing slopes receive more moisture and sunlight; rock weathering is slower. North-facing slopes receive about the same amount of precipitation as south-facing slopes; less moisture evaporates from north-facing slopes. South-facing slopes receive less moisture, yet rock weathering is faster.

C

The finely divided, red, brown, and yellow soil-coloring minerals originate by what process? mechanical weathering of very fine-grained, blue-gray clays chemical weathering of quartz and feldspars precipitation of iron oxides during the chemical weathering process mechanical weathering of the feldspars and micas in granite and rhyolite

C

What is a bittern? an evaporate sedimentary rock rich in gypsum and halite the dark-gray, clay-rich matrix of an arkose residual brine left after precipitation of halite an algal limestone mound deposited in an atoll lagoon

C

What is probably the single most important, original, depositional feature in sedimentary rocks? sizes of the sand grains degree of lithification bedding or stratification compaction of the mud and clay

C

Which of the following applies to the basic constituents of halite, gypsum, and sylvite? transported as dissolved ions; deposited as detrital mud transported as detrital mud; deposited by evaporation transported as dissolved ions; deposited by evaporation transported and deposited as mud-sized particles

C

Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks? Evaporate minerals are more soluble than quartz and less soluble than calcite. Evaporate minerals are less soluble than quartz and calcite. Evaporate minerals are more soluble than calcite and quartz. Evaporate minerals, quartz, and calcite all have the same relative solubility.

C

Which of the following statements concerning humus is not true? is typically found above the B soil horizon consists of decaying and partly decayed leaves and other plant materials is readily leached from the B horizon in weakly acidic, soil solutions is less abundant in wet, tropical, forested areas than in temperate, forested areas

C

Which of the following statements concerning lateritic soils is generally not true? They form in warm, moist, tropical climates They are mainly red in color They remain highly productive argricultually without additions of fertilizers. They consist of only the most insoluble, soil-forming minerals such as iron oxides, aluminum oxides, and clays.

C

Which of the following would retain the most detailed impressions of fossilized organisms? very fine-grained volcanic ash deposited in an ancient lake an ancient, rainforest lateritic soil buried by basalt lava flows quartz-rich sand deposited in shallow, beachfront environment gravel and sand stream deposits laid down during flash floods

C

Which one of the following statements best describes erosion? disintegration and decomposition of rocks and minerals at the surface movement of weathered rock and regolith toward the base of a slope the process by which weathered rock and mineral particles are removed from one area and transported elsewhere the combined processes of leaching, eluviation, and mass wasting

C

Which statement concerning sedimentary rocks is not true? They may contain fossils that provide clues about ancient life forms. They probably show some evidence of stratification. They were originally deposited at depth below the bottom of the sea. They are composed of particles and constituents derived from weathering and erosion of other rocks.

C

Which term best describes those processes that move weathered rock materials and soils downslope? podzolization slope sheeting mass wasting talus transfer

C

_________ sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock Quartz-rich Lignitic Arkosic Oolitic

C

__________, a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks. Calcite Orthoclase Quartz Biotite

C

A cherty limestone would contain which major constituents? iron oxide, calcite silica; iron oxide clay minerals silica; calcite

D

Caliche is an excessive accumulation of __________. calcite in the E horizon of a pedalfer clays in the A horizon of a laterite clays in hardpan layers of a pedocal calcium carbonate in the B horizon of a pedocal

D

In which area are pedocal soils most likely to be found? a tropical rainforest in the Amazon Basin of Brazil a bitterly cold, permafrost area in north-central Siberia a forested area of the southeastern United States a moderately dry to semiarid grassland such as the western Great Plains

D

In which area would weathering by frost wedging probably be most effective? in a moist, tropical forest in cool high desert areas where the subsoil is permanently frozen in moist, temperate climates

D

What is the chemical formula for dolomite, the major mineral in dolostones? NaCl CaSO4 2H2 0 SiO2 CaMg(CO3 )2

D

What mineral particles are the dominant coloring agents in reddish, brownish, and yellowish soils? soluble potassium and sodium bicarbonates humus and calcium carbonate very fine-sized, silica and calcite particles dust-sized grains of iron oxides

D

What two factors speed up rates of chemical reaction and weathering in rocks and soils? low temperatures; very dry low temperatures; very moist high temperatures; very dry warm temperatures; very moist

D

Which of the following best describes bedded gypsum and halite? detrital sedimentary rocks varieties of dolostone varieties of coal and peat evaporates; chemical, sedimentary rocks

D

Which of the following is / are most susceptible to chemical weathering by dissolution? quartz clay minerals iron oxides calcite

D

Which of the following sedimentary rocks would you expect to have originally been deposited by fast-moving streams? mudstone oolitic limestone graywacke conglomerate

D

Which one of the following is an important, mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock? oxidation eluviation hydrologic cycling frost wedging

D

Which one of the following statements concerning mechanical weathering is not true? reduces grain sizes of rock particles allows for faster rates of chemical weathering is important in the formation of talus slopes involves a major change in the mineral composition of the weathered material

D

Which term best describes an accumulation of angular rock fragments at the base of a steep, bedrock slope or cliff? trellis slope taliche slope tellus slope talus slope

D

Which type of limestone consists mainly of tiny, marine fossils composed of calcite? dolostone chert coquina chalk

D

_________ cement produces bright-red and yellow colors in some sandstone Clay Calcite Quartz Iron oxide

D

__________ are further concentrated in a residual brine after NaCl is crystallized. Iron, sodium, and chlorine Magnesium, calcium, and sulfur Calcium, sulfur, and titanium Potassium, magnesium, and bromine

D

_________ is not a common cementing agent for sandstones. 23 Quartz Calcite Fluorite Iron oxides

c