Earth - An Introduction to Physical Geology Part 2

Word Analysis Questions 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. 1) A) frost wedging Answer : B) mass wasting C) sheeting D) oxidation B) dissolution C) hydrolysis D) sheeting mass wasting 2) A) oxidation Answer : sheeting 3) A) surface area Answer : B) rock characteristics C) geologic age geologic age 4) A) topography Answer : B) time C) parent material D) elevation B) A horizon C) E horizon elevation 5) A) C horizon Answer : C horizon 6.3 20 D) B horizon D) climate True/False Questions 1) Quartz weathers readily to aluminum -rich clay minerals. Answer : FALSE 2) Abundant moisture and warm temperatures result in high rates of chemical weathering. Answer : TRUE 3) Very fine-grained, iron oxide particles account for nearly all red, yellow, and brown soil colors. Answer : TRUE 4) In pedalfer soils, the B horizon is enriched in calcite and humus. Answer : FALSE 5) Pedocal soils typically form by intense chemical weathering under very cold and wet climatic conditions. Answer : FALSE 21 6) Pedalfers form more readily than pedocals under conditions of low soil moisture content. Answer : FALSE 7) Oxidation of iron is an important chemical weathering process for ferromagnesian silicate minerals like olivine and biotite. Answer : TRUE 8) Sheeting is mainly a process of mechanical weathering. Answer : TRUE 9) Sheeting fractures and exfoliation domes commonly develop in areas with soft, highly fractured bedrock. Answer : TRUE 10) Quartz is quite resistant to weathering and is an important component of sands in riverbeds and on beaches. Answer : TRUE 11) Feldspars commonly decompose during weathering to clay minerals, silica, and soluble constituents. Answer : 22 TRUE 12) Humus is a concentration of decaying, organic matter in the B horizons of lateritic soils. Answer : FALSE 13) Calcite, a major component of some monumental and building stones, slowly dissolves in weakly acidic waters. Answer : TRUE 14) Like most other liquids, water decreases in volume when it freezes. Answer : FALSE 15) Chemical weathering in bedrock below the land surface often begins along joints and sheeting fractures. Answer : TRUE 16) Removal of soluble chemical constituents from a soil is termed leaching. Answer : TRUE 17) The material caliche represents an extensive, concrete -like accumulation of calcite in the B horizon of a pedalfer soil. Answer 23 FALSE 18) The solum or true soil includes all horizons above the C horizon. Answer : TRUE 19) Ferromagnesian minerals (like olivine and pyroxene) that crystallize at high temperatures in Bowen's reaction series are generally much less susceptible to chemical weathering than quartz. Answer : FALSE 20) Decomposition of pyrite is an important factor in generating acidic mine drainage. Answer : TRUE 6.4 Short Answer Questions 1) What kind of weathering involves only a reduction in the sizes of bedrock, regolith, and mineral particles? Answer : mechanical 2) Half Dome in Yosemite National Park, California, and Stone Mountain in Georgia, are shaped mainly by what mechanical weathering process? Answer : sheeting 24 3) Which form of chemical weathering specifically affects the iron contained in ferromagnesian, rock-forming, silicate minerals? Answer : oxidation 4) What is the most abundant, naturally produced, weak acid involved in chemical weathering and soil formation? Answer : carbonic 5) The very fine-sized, clay mineral particles move downward from the A to the B horizon of some soils. What is this process called? Answer : eluviation 6) Under most weathering conditions, which mineral component of granites and rhyolites would be most resistant to decomposition? Answer : quartz 7) What term describes the layer of partly decayed plant matter at the top of the soil profile in most forested areas? Answer : humus 8) What term refers to removal of soluble constituents from soils? Answer 25 leaching 9) Which term denotes the true soil above the zone of partly weathered bedrock? Answer : solum 10) What term describes a soil that has developed from silt and clay deposited by a flooding river? Answer : transported 11) Would you call the loose, unconsolidated, surface material on Mars regolith or soil? Answer : regolith 6.5 Critical Thinking Questions Use complete sentences, correct spelling, and the information presented in Chapter 6 to answer the questions below 1) Would mechanical or chemical weathering be significant processes on the Moon or another planet in our solar system? Why or why not? Name at least two characteristics or factors here on Earth that allow for weathering to be a significant geologic process. 2) Compare and contrast soil formation between an arid region underlain by quartz sandstone and a temperate climate in an area composed of granite. Include a discussion of the major factors influencing soil formation and the role of each in both regions. 3) As a geologist employed by an engineering firm, your first assignment is to assess the 26 potential for soil erosion on a 2000-acre site. There has been no previous development on the property, which consists of roughly equal portions of farmland, forests that have recently been cut down, and hilly terrain with native vegetation. Briefly outline your approach for assessment including what factors are important for your study, which areas have a higher potential for erosion problems, and what steps you might suggest to prevent or lessen soil erosion. 27 6.6 Visualization Questions 1) What process does the diagram below illustrate? Answer : sheeting 2) What is the feature labeled "A" in the diagram below? Also, how did it form? 28 Answer : talus slope. Rocks fell from the adjacent rocky cliff and accumulated at the base of the cliff as a talus slope. 29 3) 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) ________ Answer : a) D b) A c) B d) B 30 4) Fill in the blanks on the diagram below with the names of the soil "layers" that are labeled. Answer : a) O horizon b) A horizon c) B horizon d) C horizon 31