Brianna_Monteil_Chapter_5

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Metropolitan Community College, Kansas City *

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101

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Geology

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Oct 30, 2023

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docx

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Chapter 5 Weathering, Erosion, and Sedimentary Rocks Assignment 1. What are the two basic categories of weathering and how do the products of each category differ? The two different categories of weathering are mechanical and chemical. Mechanical weathering is when there is pressure involved like expansion, frost and root wedging, and salt expansion. Chemical weathering includes carbonic acid and hydrolysis, dissolution, and oxidation. 2. When a rock is mechanically weathered, how does its surface area change? How does this influence chemical weathering? A rock’s surface area changes from mechanical weathering because of the breaking down of a rock into smaller pieces. This can influence chemical weathering by giving it more area and opportunity to take place. 3. How do joints promote weathering? Joints promote weathering by allowing water to flow through them and start the weathering process before the rock is even exposed. 4. How is carbonic acid formed in nature, and what occurs when carbonic acid reacts with limestone or marble? Carbonic acid is formed when carbon dioxide dissolves in water. This occurs naturally through clouds. When carbonic acid reacts with limestone or marble, it dissolves small amounts of the calcite found in the rock and carries it away through the cracks and pores which then leaves behind an opening. 5. List the five basic controls of soil formation and which factor is most influential in soil formation. ● the mineralogy of the parent material ● topography ● weathering ● climate ● the organisms that inhabit the soil Climate is the most influential factor in soil formation. 6. Outline the steps that would transform an exposure of granite in the mountains into various sedimentary rocks. ● Weathering ● Soluble materials are carried off by runoff and groundwater ● Wind and water currents slow, ice melts, solid particles are deposited ● Materials are dissolved in water and get deposited and the materials are precipitated ● More deposits happen and the older sediments get buried below layers. Over time, the sediments convert to sedimentary rocks

7. List and briefly distinguish among the three basic sedimentary rock categories. ● Clastic – formed from other pieces of rocks ● Organic – formed from plants, animals, and other organisms ● Chemical – formed when water seeps through the rock and dissolves some material 8. Describe how sediments become sorted and rounded. Sorting is what describes the grain sizes of sediments or sedimentary rocks. Sorting is used to determine the type of erosion that creates the rocks. Rounding is when the edges of a rock is removed because of abrasion during transport. 9. What are the two categories of chemical sedimentary rock? Give an example of a rock that belongs to each category and explain why. ● Biochemical – limestone is an example of biochemical because it is formed from biological processes ● Inorganic – gypsum is an example of inorganic because it evaporates and leaves behind an excess amount of salt 10. How might sedimentary structures be useful clues about the geologic past? Pick a sedimentary environment and explain the type of sediment, sediment size, sedimentary rock type, and sedimentary structures that would be typical of that sedimentary environment. Sedimentary structures are useful clues about the geological past because they determine minerals, geologic structure, and information about the environment. Rivers include dissolved, suspended, and bedload kinds of sediments that are usually small in size. Rivers are abundant in sandstone, limestone, and shale and are made up of herringbone cross-stratification, flaser bedding, and interference ripples.

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