Midterm Rock Identification - EES 1510L

Rhyolite

- Igneous rock
- Felsic
- Fine-grained crystalline
- Fast cooling rate
- Came from an extrusive, explosive eruption
- Continental setting

Andesite

- Igneous rock
- Intermediate
- Fine-grained crystalline
- Fast cooling, extrusive rock

Basalt

- Igneous rock
- Mafic
- Fine-grained crystalline
- Cooled very quickly
- Effusive eruption

Granite

- Igneous rock
- Felsic
- Course-grained crystalline

Diorite

- Igneous rock
- Intermediate
- Course-grained crystalline

Gabbro

- Igneous rock
- Mafic
- Course-grained crystalline

Peridotite

- Igneous rock
- Ultramafic
- Course-grained crystalline

Pumice

- Igneous rock
- Glassy

Obsidian

- Igneous rock
- Glassy

Welded Tuff

- Igneous rock
- Fragmental

Breccia

- Sedimentary rock
- Clastic
- Gravel-sized particles
- Angular, poorly sorted
- Formed in an environment close to the source

Conglomerate

- Sedimentary rock
- Clastic
- Gravel sized particles, with some silt and sand
- Poorly sorted
- Subrounded/subangular
- Formed in a high energy river

Quartz sandstone

- Sedimentary rock
- Clastic
- Particle size: sand
- Well-sorted
- Sub-rounded/rounded
- Formed in a river or beach

Siltstone

- Sedimentary rock
- Clastic
- Particle size: silt
- Formed in a low energy environment but higher than shale: probably small river or offshore marine

Shale

- Sedimentary rock
- Clastic
- Clay-sized particles
- Well-sorted
- Low energy environment

Fossiliferous limestone

- Sedimentary rock
- Biochemical
- Reacts with HCl
- Has fossils
- Formed in shallow warm marine water

Chalk

- Sedimentary rock
- Biochemical rock
- Reacts with HCl
- Formed in a deep marine, low energy environment

Halite

- Sedimentary rock
- Chemical
- Shallow water, pools evaporate

Chert

- Sedimentary rock
- Chemical
- Includes silica
- Well-sorted
- Formed in a shallow-marine area

Coal

- Sedimentary rock
- Organic
- Formed in a swamp (low energy)

Slate

Foliated
Low-Grade Metamorphism
Protolith: Shale

Schist

Foliated
Intermediate-Grade Metamorphism
Protolith: Shale

Phyllite

Foliated
Intermediate-Grade Metamorphism
Protolith: Shale

Gneiss

Foliated
High-Grade Metamorphism
Protolith: Shale/Granite/+more

Quartzite

Non-foliated
Intermediate-Grade Metamorphism
Protolith: Quartz Sandstone

Marble

Non-foliated
Intermediate-Grade Metamorphism
Protolith: Fossiliferous Limestone

Shale Protolith Processes

Neocrystallization

Quartz Sandstone and Fossiliferous Limestone Protolith Processes

Recrystallization

Mineral

a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form

Rock

A naturally occurring solid mixture of one or more minerals or organic matter

Limestone rocks

more animals, and CaCO3 does not dissolve in warmer water; Form in calmer, warmer environments with more animals

Symmetrical Ripples

Formed from bidirectional currents that oscillate

Asymmetrical Ripples

Form from asymmetrical ripples such as rivers/winds

Cross-bedding

produced when dunes or ripples are stacked on top of each other. Sediment is deposited at the angle of the flowing water or wind, which transports it.

Mudcracks

commonly seen due to the sediment being regularly exposed to air during low tides

Things each type of rock have in common:

• Igneous

  • Interlocking minerals can vary in size due to the cooling rate

• Sedimentary

  • Layered and visible fragments of other rocks and fossils

• Metamorphic

  • Foliated or non-foliated

Elevation Map

Major lines are about 10 units apart and elevation increases as you go towards the center of the map

How to create an elevation profile

Draw a line and use that to create an elevation where:

• X-axis is the distance from the origin

• Y-axis is the elevation

What determines decay?

• the decay rate

• initial quantity of material

• time passed in an isotopic system

Decay Equation

N = N_oe^-At

Note: the decay constant is always positive

The lost of initial daughter product does what (in terms of decay and age) ?

Underestimate of age

Additional daughter product does what (in terms of decay and age) ?

Artificially inflating the apparent age of the rock/mineral

Crystalline structure

Internal bonding/arrangement

Crystal habit

External shape of a crystal

Are crystalline structures and crystal habits always the same?

Crystalline structure does not equal crystal habit due to blockers (other rocks or minerals) that inhibit the minerals from growing into their crystal habit.

Cleavage

a mineral's property to break along specific planes when struck; break or split apart with smooth surfaces

Fracture

a mineral breaks with a rough or jagged surface

Conchoidal fracture

fracture with smooth, curved surfaces that resemble the interior of a seashell

Striations

parallel scratches or grooves in a rock surface that are created by geological processes

Felsic rocks tend to be more

light in color

Mafic rocks tend to be more

dark in color

Density

Mass over volume (mass must be in grams and volume must be cm³)

Continental Crust

Density (average)	Layer Thickness	Properties
2.8 g/cm³	30-40 km	solid

Oceanic Crust

Density (average)	Layer Thickness	Properties (highlight property)
3.0 g/cm³	5-10 km	solid

Mantle

Density (average)	Layer Thickness	Properties (highlight property)
3.4-5.4 g/cm³	2850 km	solid/liquid

Outer Core

Density (average)	Layer Thickness	Properties (highlight property)
10-12.3g/cm³	2260 km	liquid

Inner Core

Density (average)	Layer Thickness	Properties (highlight property)
15g/cm³	1220 km	solid

Pressure forces it to be solid

Which rock sample (basalt, granite, peridotite) represents the best match for:

1. Continental Crust: Granite

2. Oceanic Crust: Basalt

3. Mantle: Peridotite