GLS100-01 Quiz#7 chapters 5 and 6 Fall 2009 Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Clay minerals formed from gabbro or diorite bedrock illustrate which kind of weathering? 1) A) mechanical B) proactive C) chemical D) syntropical 2) Frost wedging is the major weathering process contributing to the formation of which regolith material? A) mature pedalfers B) tropical laterites C) talus slopes D) C soil horizons 2) 3) What portion of an angular, fracture-bounded granitic block shows the highest rate of weathering? 3) A) the edges and corners B) the unfractured interior C) the crack surfaces not including edges and corners D) all of the above show equal rates 4) Which term best describes those processes that move weathered rock materials and soils downslope? A) podzolization B) talus transfer C) mass wasting D) slope sheeting 4) 5) Which one of the following statements concerning mechanical weathering is not true? 5) A) allows for faster rates of chemical weathering B) involves a major change in the mineral composition of the weathered material C) reduces grain sizes of rock particles D) is important in the formation of talus slopes 6) Which one of the following statements best describes erosion? 6) A) disintegration and decomposition of rocks and minerals at the surface B) the combined processes of leaching, eluviation, and mass wasting C) the process by which weathered rock and mineral particles are removed from one area and transported elsewhere D) movement of weathered rock and regolith toward the base of a slope 7) Clay minerals, silica (SiO2), and dissolved potassium bicarbonate in the soil water are products of which process? A) chemical weathering of orthoclase feldspar B) mechanical weathering of granite and rhyolite C) differential mechanical weathering of micas D) chemical weathering of olivine and plagioclase feldspar 7) 8) What two factors speed up rates of chemical reaction and weathering in rocks and soils? 8) A) warm temperatures; very moist B) low temperatures; very dry C) high temperatures; very dry D) low temperatures; very moist 1
9) From the land surface downward to the unweathered bedrock, which of the following is the correct order of the different soil horizons? A) E, A, B, C, 0, bedrock B) 0, A, E, B, C, bedrock C) A, B, C, D, E, bedrock D) D, E, C, B, A, bedrock 10) Which one of the following is an important, mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock? A) hydrologic cycling B) oxidation C) frost wedging D) eluviation 9) 10) 11) What two, chemical constituents cannot form by chemical weathering of the feldspar minerals? 11) A) insoluble iron oxides and soluble magnesium bicarbonates B) silica and soluble calcium bicarbonate C) silica and insoluble clay minerals D) soluble sodium and potassium bicarbonates 12) Under similar warm, moist climatic conditions, why would basalt and gabbro generally have higher chemical weathering rates than rhyolite and granite? A) the quartz in the gabbro and basalt decomposes very quickly B) the ferromagnesian minerals in the gabbro and basalt are subject to oxidation and chemical breakdown C) the potassium feldspars and quartz in the rhyolite and granite are more susceptible to cracking by frost wedging D) the plagioclase feldspars in the granite and rhyolite decompose readily to clay minerals and iron oxides 12) 2
13) Carefully examine the illustration below and the features labeled A through D. Give a letter (A, B, C, or D) for each answer below. At which location would the thickest residual soil develop? (a) At which location would the greatest amount of frost wedging occur? (b) At which location would the thickest transported soil develop? (c) At which location would there be the most unconsolidated deposits? (d) 14) Fill in the blanks on the diagram below with the names of the soil "layers" that are labeled. 3
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 15) 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? A) limestone representing lithified coral-reef carbonates B) sandstone lithified from quartz-rich beach sand C) a thin, upper, mudstone portion of a thick graywacke bed with graded bedding D) evaporite deposits of gypsum and salt 15) 16) Which of the following is not a type of limestone? 16) A) travertine B) arkose C) chalk D) coquina 17) A cherty limestone would contain which major constituents? 17) A) clay minerals B) silica; iron oxide C) silica; calcite D) iron oxide, calcite 18) Nonclastic textures are common in which of the following sedimentary rocks? 18) A) boulder breccias B) cherty conglomerates C) sandstones D) limestones 19) Which of the following sedimentary features can each be used to determine paleocurrent directions? A) fossils and mud cracks B) mud cracks and ripple marks C) ripple marks and cross stratification D) grain size sorting and ripple marks 19) 20) What is probably the single most important, original, depositional feature in sedimentary rocks? 20) A) bedding or stratification B) degree of lithification C) sizes of the sand grains D) compaction of the mud and clay 21) Detrital sedimentary rocks are classified (named) based on the. 21) A) degree of compaction and lithification B) compositions of soluble minerals C) grain sizes of the detrital particles D) colors of the cementing minerals 22) is not a common cementing agent for sandstones. 22) A) Quartz B) Iron oxides C) Fluorite D) Calcite 23) Which statement concerning sedimentary rocks is not true? 23) A) they are composed of particles and constituents derived from weathering and erosion of other rocks B) they probably show some evidence of stratification C) they were originally deposited at depth below the bottom of the sea D) they may contain fossils that provide clues about ancient life forms 24) Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks? A) evaporate minerals are more soluble than calcite and quartz B) evaporate minerals are more soluble than quartz and less soluble than calcite C) evaporate minerals are less soluble than quartz and calcite D) evaporate minerals, quartz, and calcite all have the same relative solubility 24) 4
25) What is the main difference between a conglomerate and a sedimentary breccia? 25) A) breccia clasts are the size of baseballs; conglomerate clasts are larger B) a breccia is well stratified; a conglomerate is poorly stratified C) breccia has a compacted, clay-rich matrix; conglomerate has no matrix D) breccia clasts are angular; conglomerate clasts are rounded 26) Carefully observe each of the photographs below of sedimentary rocks. To the right of each sample, name the rock and describe its origin (how it formed). (a) (b) (c) 5