HW 02
Chapter 2
1. Explain the statement “One rock is the raw material for another” using the rock cycle.
There are three primary rock cycles: igneous, sedimentary, and metamorphic. There are five rock processes: 1. cooling crystallization; 2. weathering, transport, and deposition; 3. lithification (compaction, cementation); 4. metamorphism (heat, intense pressure); and 5. melting.
The first process is the crystallization of the magma boiling into lava that cools to solidify igneous rock. Over time, igneous rock weathering breaks down the rock to transport and deposit sediment that compacts and is cemented into lithification form. Over the years, sedimentary rock is buried deep into the earth’s crust, where metamorphism heats and pressures the rock back into magma.
3. What does a porphyritic texture indicate about the history of an igneous rock?
The porphyritic texture is a large mass of magma solidifying thousands or millions of years.
5. Relate the classification of igneous rocks to Bowen’s reaction series.
The classifications of igneous rocks are composition group felsic, mafic, andesitic, and ultramafic. Bowen reaction series is the revolution of the magma temperature process of the crystallization level that can produce a specific rock type.
7. How does mechanical weathering add to the effectiveness of chemical weathering?
The weathering of rocks helps break apart the earth’s material with the changing of our environment seasonally: frost, freezing rain, and cold or warm air play an integral part in the rock cycle. Rainwater or frost can cause the oxidizing or decomposing of rock formation.
9. Which minerals are most common in detrital sedimentary rocks? Why are these minerals so abundant?
The two most common detrital sedimentary rocks are clay and limonite, minerals formed by chemical weathering with iron in soil and sedimentary rock.
11. Distinguish between the two categories of chemical sedimentary rocks.
The distinction between chemical sedimentary rocks is in contrast to clastic rocks, which are the solid products of weathering. The second category is organic sedimentary rock, compared to sedimentary rocks that are calcite- or silica-rich, where coal consists primarily of organic matter.
13. Compaction is an important lithification process with which sediment size?
The compaction pressure reduces the volume of sediment by tightly packing the grains together due to their size.
15. What is metamorphism?
Metamorphism changes the existing rock due to heat and pressure, altering its original chemical composition.
17. Distinguish between regional and contact metamorphism.
Contact or thermal metamorphism happens close to a body of magma driven by rising temperature. On the other hand, regional metamorphism, with direct pressure and high temperatures during mountain building, produces the most significant volume of metamorphic rock.
19. In what ways do metamorphic rocks differ from the igneous and sedimentary rocks from which they formed?
Metamorphic rock is formed when existing rocks are changed by heat, pressure, or reactive fluid deep in the earth’s crust. Igneous rocks are formed from lava and magma that cool and solidify. Sedimentary rocks are formed when particles settle out of water or air and are compacted and cemented, often through the precipitation of minerals from water. Each type of rock is formed through a different process, and the time required for each cycle to change and reform is what sets them apart.
Written by: Greg MD
Greg MD Blog 
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