Chapter 5 Test Answer Key

Rocks and Minerals II

Name___________________

1. Name the four eras of geologic time in order from the oldest era to present era.
   1. Precambrian
   2. Paleozoic
   3. Mesozoic
   4. Cenozoic
2. What was the dominant animal of the Mesozoic? Reptiles also accept "Dinosaurs"
3. What was the dominant animal of the Cenozoic? Mammals
4. What three forces cause weathering?
   1. Ice 
   2. Wind
   3. Water
5. Name the three processes that form sedimentary rocks.
   1. Cementation
   2. Compaction
   3. Recrystallization
6. How does coal form? Organic sedimentary rocks form from the build up and decay of plant and animal material. This usually forms in swamp regions in which there is an abundant supply of growing vegetation and low amounts of oxygen. The vegetation builds so quickly that new layers of vegetation bury the dead and decaying material very quickly. The bacteria that decay the vegetation need oxygen to survive. Because these decaying layers are buried so fast the bacteria use up what oxygen there is available and can not finish the decomposition of the vegetation. The overlaying layers become so heavy that they squeeze out the water and other compounds that aid in decay. This compressed vegetation forms coal. The longer and deeper that coal is buried makes it of higher quality.
7. What is the difference and the similarity of stalagmites and stalactites? Stalactites are formed by dripping ground water that has a high concentration of calcium carbonate. They form from the ceiling down. Stalactites form the same way but they grow from the ground up. 
8. What is a metamorphic rock? A metamorphic rock is formed from heat and pressure changing an already existing rock.