Chapter 3 Questions
Review Questions
1. Using the rock cycle, explain the statement "One rock is the raw material for another."
Magma deep within the Earth cools and forms igneous rock. Igneous rocks are weathered and transported through eroding forces, primarily wind and water, and these pieces of igneous rock that have been broken down are deposited as sediment. Sedimentary rock is formed from this sediment through compaction and cementation. When sedimentary rock is buried deep in Earth’s crust, the heat and pressure turn the sedimentary rock into metamorphic rock.
2. If a lava flow at Earth's surface had a basaltic composition, what rock type would the flow likely be (see Figure 3.7)? What igneous rock would form from the same magma if it did not reach the surface but instead crystallized at great depth?
Basalt; Gabbro
3. What does a porphyritic texture indicate about the history of an igneous rock?
Magma already containing large crystals suddenly erupted at the surface, causing the remaining molten portion of lava to cool quickly
4. How are granite and rhyolite different? The same? (See Figure 3.11.)
Rhyolite and granite are both granitic or felsic rocks chemically, but granite is coarse-grained while rhyolite is fine-grained.
5. Relate the classification of igneous rocks to Bowen's reaction series.
The classification of igneous rocks relates to Bowen’s reaction series because the series is based on the temperature at which minerals crystallize, which is also a way to classify igneous rocks
6. What minerals are most common in detrital sedimentary rocks? Why are these minerals so abundant?
Clay and quartz minerals are common in sedimentary rocks because clay is the most abundant product of chemical weathering of silicate materials and quartz is extremely durable and resistant to chemical weathering.
7. What is the primary basis for distinguishing among various detrital sedimentary rocks?
Particle size is the primary basis for distinguishing among various detrital sedimentary rocks
8. Distinguish between the two categories of chemical sedimentary rocks.
Chemical sedimentary rocks occur directly as the result of physical processes, or indirectly
through life processes of water-dwelling organisms.
9. What are evaporite deposits? Name a rock that is an evaporite.
Salt deposits that remain after arms of the sea have evaporated; halite
10. Compaction is an important lithification process with which sediment size?
Fine-grained sedimentary rocks
11. What is probably the single most characteristic feature of sedimentary rocks?
The layers that accumulate, called strata or beds
12. What is metamorphism?
Metamorphism is a process that leads to changes in the mineralogy, texture, and sometimes the chemical composition of rocks.
13. List the three agents of metamorphism and describe the role of each.
Heat- it provides the energy to drive chemical reactions that result in the recrystallization of existing minerals and/or the formation of new minerals
Confining Pressure and Differential Stress-
Confining pressure causes the space between the minerals to get close, producing a more compact rock with a greater density
Differential stress is uneven stress and causes deformation which plays a major role in developing metamorphic textures
Chemically Active Fluids- Fluids that surround mineral grains act as catalysts to promote recrystallization by enhancing ion migration.
14. Distinguish between regional and contact metamorphism.
Regional- great quantities of rock are subjected to directed pressures and high temperatures associated with large-scale deformation
Contact- change is driven by a rise in temperature within the host rock surrounding a molten igneous body
15. Which feature would easily distinguish schist and gneiss from quartzite and marble?
Schist and gneiss are foliated, meaning reorienting of the mineral grains
into a layered or banded appearance, while marble and quartzite are nonfoliated
16. In what ways do metamorphic rocks differ from the igneous and sedimentary rocks from which they formed?
The mineralogy, texture, and sometimes the chemical composition are changed.
17. List two general types of hydrothermal deposits.
Vein deposits and disseminated deposits
18. Nonmetallic resources are commonly divided into two broad groups. List the two groups and some examples of materials that belong to each.
Building materials- limestone, gypsum
Industrial materials- fluorite, corundum, sylvite