Geology Homework Questions chs 7-9

Geology Homework Questions (CHAPTERS 7-9) Chapter 7: 1. Which of these is most likely to be a biochemical sedimentary rock? - Limestone 2. Which way was the current (either wind or water) moving during deposition of this section of rocks? - toward the right 3. Which of the following can we understand by studying sedimentary rocks? - past events, such as landslides and earthquakes - how environments shifted in location through time - migration of deserts and advances of the sea - past changes in climate 4. A sandstone with a pinkish or reddish color that is the result of oxidation of iron-bearing minerals indicates the sand was: - deposited on land and exposed to air. 5. Which of the following situations would result in angular clasts? - steep slopes in a mountain 6. The natural cements that hold clasts together precipitate in the empty pore spaces after compaction. Those precipitates come from - water containing dissolved materials. 7. Most of the exposed surface of Earth is covered with - sediment and sedimentary rocks. 8. A sandstone containing mostly sand but mixed with rounded pebbles and pieces of shells indicates deposition: - by waves at the beach. 9. Melting glaciers tend to deposit most of the sediment they carry and create - at their terminus (end). 10. Which of the following environments is NOT a setting in which limestone forms? - All these are environments in which limestone forms. - (some lakes, coral reefs, deposition of calcite near springs, accumulation of the remains of microscopic organisms)

11. Clastic sedimentary rocks are classified primarily on the basis of - sediment size. 12. The two main processes by which sediment is produced are - physical and chemical weathering. 13. What type of product is being produced from material in these quarries? - Cement 14. The deep-sea floor is characterized by sediment dominated by - fine dust and the remains of single-celled organisms. 15. Sedimentary environments on land differ because of variations in - local geology. - amount of water. - topography. 16. Which environment is least likely to deposit siltstone or shale? - channel of a braided river 17. The advance of the sea across a region is known as a: - transgression. 18. Which of these is not correct in pairing how a specific mineral reacts to weathering? - All of these choices are correct. - (Quartz transforms into sand, Feldspar transforms into clay minerals, Mafic minerals transform into iron oxides.) 19. Streams deposit sediments in a __________ when they reach an ocean or lake. - Delta 20. What is the main difference between conglomerate and breccia? - the shape of the clasts 21. Bedding in sedimentary rocks is defined by: - resistance to erosion. - thickness. - color. - sediment size. 22. What is a sedimentary facies? - a sediment or sedimentary rock deposited in a specific environment 23. Which of the following processes produce sedimentary clasts? - fracturing of bedrock that results in angular pieces - decomposition of granite into quartz grains and clay - breaking of round cobbles as they are transported - scouring and abrasion of bedrock along rivers 24. Floodplains are built of - mud and sand deposited by floodwaters. 25. Which of the following is NOT involved in turning some sediment into sedimentary rock? - Metamorphism - (correct answers: cementation, burial, compaction) 26. Large, angular clasts are most likely at

- They have been transported a significant distance. 32. What setting was this sedimentary rock deposited in? - a muddy place that sometimes dried out 33. Which of the following is the most used sedimentary resource? - sand and gravel 34. In this section, a lower gray rock is successively overlain by beach sandstone, lagoon mudstone, and limestone. What is the best interpretation of what was going on? - The area was experiencing a transgression. 35. Sorting describes

- the size range of clasts in sediment. 36. Which of the following processes is NOT considered to be chemical weathering? - thermal expansion 37. Which of the following sites would contain the finest grained sedimentary deposits? - Lake at E 38. Sedimentary facies shift toward the sea as the sea moves out during a: - regression. 39. What typically happens to the size, shape, and sorting of clasts as they are transported from steep mountains toward more gentle settings? - The clasts become more rounded. 40. Sedimentary clasts are - loose fragments of rocks and minerals. 41. What do fossils pr eserved in the rock record tell us about Earth’s history? - that environments changed and the organisms that lived in them either evolved or went extinct 42. Which of the following environments would most likely consist of sand and/or rounded cobbles? - Beach at A 43. What type of rock would you form in this coral reef?

- metamorphism associated with hot seawater - tension - contact metamorphism near magma chambers - normal faults 8. Which of the following matches a sedimentary rock with a possible metamorphic equivalent? - shale – slate 9. This figure shows the settings of metamorphism in an ocean-continent convergent margin. Drag the label for each type of metamorphism to its correct position on the figure. 10. These figures show three types of geologic structures. Drag the correct label below each figure. 11. Why do rocks become stronger with depth in shallow levels of the crust? - Increasing confining pressure holds them together. 12. What type of structure is shown in this figure? - Syncline 13. What type of feature is shown in this photograph? - columnar joints 14. Which of the following features is younger than fault 1?

- lava flow and granite 15. Which location on this diagram would most likely record contact metamorphism in shallow levels of the crust? - 1 16. These figures show three types of geologic structures. Drag the correct label below each figure. 17. What kind of metamorphic rock is formed where rocks have been heated but not deformed? - a rock with metamorphic minerals but no foliation or lineation 18. Which of the following is a common metamorphic process? - rotation of minerals into a common orientation - dissolving some parts of the rock and carrying the material away - deforming objects into new shapes - remobilization of chemical constituents into light and dark bands 19. When a rock is buried deep in Earth and experiences the same force from all sides, it is under - confining pressure. 20. Fractures along which the rock has slipped relative to the other side are called - Faults 21. What type of fault forms when the hanging wall moves up in relation to the footwall? - reverse fault

29. How does schistosity develop in a metamorphic rock? - Mica flakes line up in parallel orientation due to differential stress. 30. Which of the following is NOT something we can learn by studying geologic structures and metamorphic rocks? - We can learn information about all these by studying structures and metamorphic rocks. - (correct answers: the type of fault that is present, temperature and pressure conditions of metamorphism, whether metamorphic minerals grew before or after deformation, the location of a fault in the landscape) 31. Which of the following might a geologist look for in a rock hand sample to make interpretations regarding deformation and metamorphism? - minerals that are present - observed sequence of minerals - mineral chemistry 32. What kind of structure is shown in this image? - strike-slip fault 33. In what environments does low pressure/high temperature metamorphism occur? - near magma but at shallow levels 34. This image is demonstrating chemical __________ during metamorphism and deformation. - Remobilization 35. What type of stress is the cause of most folding? - Compression 36. What type of metamorphism dominates a continental collision? - regional metamorphism 37. Which location on this diagram would most likely record metamorphism along a subduction zone?

- 3 38. Which location on this diagram would most likely record hot conditions deep within the continental crust? - 4 39. Which of the following characterizes a continental rift? - contact metamorphism near magma chambers - metamorphism associated with shearing - normal faults - tension 40. What type of deformation is shown in this photograph? - Displacement

- C 3. Which of the following time periods were dinosaurs the dominant creatures? - Mesozoic 4. What factors are the most critical in determining whether a fossil is preserved? - whether the creature had hard parts and how fast it was buried 5. What events have occurred to generate the geologic setting on the right from the one on the left? - The surface has been eroded by streams. - The ocean has withdrawn. - The rocks have been folded. 6. How did an oxygen-rich atmosphere develop from a carbon dioxide-rich atmosphere? - through photosynthesis by cyanobacteria 7. Which of these gases was lacking in Earth’s earliest atmosphere? - Oxygen 8. These figures show three types of unconformities. Drag the name for each type of unconformity to the correct figure. 9. The term half-life represents the time it takes - for half of the parent atoms to decay into daughter atoms. 10. What were some of the earliest forms of life on Earth? - microscopic creatures that built mound-shaped structures called stromatolites

11. What defines the boundaries between each of the three eras in the geologic timescale? - two great mass extinctions 12. This figure shows the main subdivisions of the geologic timescale. Which of these is the Precambrian? - D 13. Which of the following is NOT accurately dated at between 4 and 4.6 billion years old? - isotopic ages on Earth’s oldest known fossil shell - (correct answers: age of the oldest meteorites, age of moon rocks returned to Earth and dated, the oldest dates on mineral grains on Earth) 14. Which of the following is NOT something we can learn by determining isotopic ages? - We can determine all of these. - (the age of material from which clasts in a sedimentary rock were derived, the age of a volcanic eruption, the age when a rock is uplifted toward the surface, the cooling history by using different types of isotopic ages) 15. What do tree rings, ice cores, and varves have in common that can be used to show that the history of Earth is not short? - They show annual cycles of growth or change that we can measure back 10,000 to 100,000 years ago. 16. When did the Great Dying occur? - 252 million years ago 17. Which of the following materials can be dated with carbon-14 at archaeology sites? - bones - charcoal - wood 18. Unit C is present in the left column but not the right column because

27. Drag the figures so that they are in the correct order, arranged from oldest at the top (1) to youngest at the bottom (5). Move your cursor over position in the right column to get hints about that event. 28. Why don’t these two sequences of fossil-bearing rocks match exactly? - They have different histories of erosion and deposition. 29. Which principle can be used to determine the relative age of an igneous intrusion called a dike? - cross-cutting relations 30. Which isotopic system would we use to date very young geologic deposits? - carbon-14 31. What is a trace fossil? - a preserved feature made by an animal as it moved across or within soft sediment 32. Which principle is used to determine the age of rocks by ordering them from oldest on the bottom to the youngest on the top? - Superposition 33. What is evident in the rock record following and likely linked to the second Great Oxygenation event? - the first appearance of red-colored sedimentary rocks 34. How does an angular unconformity form? - Older rocks are tilted, eroded, and overlain by younger rocks.

35. Drag events so that they are in the correct order, from oldest at the bottom (6) to youngest at the top (1). 36. What processes oxygenated Earth’s early atmosphere? - cyanobacteria photosynthesis 37. This figure shows the main subdivisions of the geologic timescale. Which of these is the Mesozoic? - B 38. Which of the following is NOT a way in which fossils can be preserved? - All these are ways a fossil can be preserved. - (They can be replaced by hard materials, such as silica; They can be too small to see but can build diagnostic features in the rocks; They can be preserved in ancient tree sap; They can be buried and decay, leaving a cavity in the rock)