formation of rocks

Question 1

What are sedimentary rocks products of?

Answer 1

The lithification of particles produced by the weathering of other preexisting rocks

Question 2

What can sedimentary rocks comprise of?

Answer 2

• parent material from older igneous, metamorphic, and even sedimentary rocks
• mineral fragments
• organic material
• minerals that precipitate from solution

Question 3

What are the components called?

Answer 3

sediments

from the Latin “sedentarius, which means “sitting”

Question 4

What are clastic sedimentary rocks?

Answer 4

• these rocks came from the cementation of sediments that have been deposited, buried, and compacted over a long period of time
• they are differentiated based on the size of the sediments/clasts of the rocks

ex. shale, sandstone, and conglomerate

Question 5

What are chemical sedimentary rocks?

Answer 5

• these rocks come from the precipitation of minerals from ions in solution
• usually occur underneath the surface (not as deep as igneous)

process: rocks are exposed to water and oxygen -> undergo chemical changes like oxidation (rusting) and hyrdolysis -> breaks rocks into their chemical components (ions) -> ions carried by running water -> minerals form bc it’s saturated by those ions

ex. limestone, dolostone, rock salt

Question 6

What are bioclastic sedimentary rocks?

Answer 6

• these rocks are formed from the compaction and cementation of plant and/or animal remains

ex. coquina, organic limestone

Question 7

What are metamorphic rocks made out of?

Answer 7

They are made out of preexisting or parent rocks that are altered by heat, pressure, and chemical activity of fluids

process of metamorphism - “change in form”

Question 8

What can metamorphic rocks be comprised of?

Answer 8

igneous, sedimentary, and metamorphic rocks

Question 9

What are metamorphic rocks when the dominant factor is pressure?

Answer 9

• foliated metamorphic rocks
• usually due to tectonic activity
• this type of metamorphism is called regional metamorphism bc tectonic plates are involved (which create mountain chains)

ex. slate, schist, gneiss

Question 10

What are metamorphic rocks when the dominant altering factor is heat?

Answer 10

• nonfoliated metamorphic rocks
• usually from direct contact between an older rock material and an intruding body of magma
• recrystallization, or change in mineralogy (if chemically-active fluids are involved)
• process is called contact metamorphism

ex. marble, quartzite

Question 11

When can metamorphism immediately happen?

Answer 11

from instantaneous events:
- dynamic metamorphism - faulting
- shock metamorphism - meteorite impact

*heat & pressure are still dominant

Question 12

When are igneous rocks formed?

Answer 12

When magma or lava cools and solidifies into rock

Question 13

What are igneous rocks formed below the surface?

Answer 13

• intrusive or plutonic
• formation of crystals are visible to the naked eye
• cool underneath the surface as plutons

ex. granite, diorite, and syenite

Question 14

What are igneous rocks formed on the surface from rapidly cooling lava?

Answer 14

• extrusive or volcanic
• usually extruded during volcanic eruptions
• formation of very small crystals (visible w/ magnifying glass)

Question 15

What are igneous rocks formed on the surface from the consolidation of particles erupted by explosive volcanic activity?

Answer 15

• pyroclastic igneous rocks
• particles come together on the surface via lithification
• pyroclastic rocks are a hybrid of igneous and sedimentary

ex. volcanic breccia, tuff, ignimbrite (adobe)