Unit 1: Geology Flashcards
Define Sedimentary, Metamorphic and Igneous rocks
Sedimentary: Rocks that are formed from the accumulation of mineral or organic particles that is later cemented
Metamorphic: Rock that is formed from increasing heat and pressure
Igneous: Rock that is derived from magma
What are the 2 types of igneous rocks? What kind of textures do they exhibit?
Plutonic/Intrusive: Formed from the slow cooling of magma in chambers below the earths surface. Exhibit a phaneritic texture (larger, coarse crystals)
Extrusive/Volcanic: Formed form the fast cooling of lava above the earths surface. Exhibit a aphanitic texture (finer, small crystals hard to discern with the naked eye
What is the difference between Mafic and Felsic rocks?
Mafic: darker; higher concentration of iron and magnesium; denser
Felsic: lighter; higher concentration of silicates; less dense
What causes a porphyry?
A 2 stage cooling process
- Magma cools slowly allowing for large crystals
- Magma moves upwards and/or erupts allowing for faster cooling
(large crystals in a fine-grained matrix)
What are the two types of Metamorphic rocks formation?
Contact: Metamorphism of non-foliated rocks by contact with magma
Regional: Metamorphism as a result of increased heat and pressure; causes foliation
What is the difference between low grade and high grade metamorphic rocks?
Low grade, which begins at temperatures and pressure just above sedimentary rocks, is the early stages of metamorphism and becomes the parent rock for high grade metamorphic rocks
High grade metamorphic rocks are usually coarse grained and exhibit more banding and folds from higher heat and pressure
Slate > Shale > Phyllite > Schist > Gneiss
(Parent)
What is foliation?
Layered texture; alignment of grains; generally from regional metamorphism
What are the three types of sedimentary rocks?
Clastic: Made up of clasts (pieces of existing rock) loosened by weathering which are compacted, cemented and lithified
Chemical: Chemical precipitation; water dissolve parts of rocks which is carried away. The water then precipitates, evaporates, and the deposited minerals form new rocks (limestone, halite, gypsum)
Biologic: Living organisms die and are pressed and cemented together (coal, limestone, coquina)
What are the two types of conglomerates?
Breccia: Angular clasts
Rounded: rounded clasts; pebbles and boulders
In what form is sediment usually deposited?
typically deposited in layers containing many features (beds from water or wind); stratified
What are the different clast sizes?
Clay: < 0.005mm
Silt: 0.005mm - 0.063mm
Sand: 0.063 - 2mm
Pebbles: 2mm - 64mm
Cobble: 64mm-256mm
Boulder: >256mm
What are the 4 main layers of the Earth?
Inner Core
Outer Core
Mantle
Crust
What are the 5 spheres of Earth?
Lithosphere - solid, outer part of the earth
Cryosphere - the frozen water on earth
Atmosphere - THE AIR
Hydrosphere - water on the surface, underground, in air
Biosphere - Biotic things
What is a rock?
An AGGREGATE of minerals
What is a mineral?
A naturally occurring inorganic substance with a distinct chemical composition and ordered arrangement of atoms
