Geology Exam 3

Loose fragments of rocks and minerals, shells, or mineral crystals that precipitate out of water

Weathering

Breaks rocks into unconnected clasts of variable size (ex. jointing, frost wedging, root wedging, and thermal expansion)

Shapes and roundness of grains. A rounder, smaller grain likely weathered for longer and/or traveled farther. And vice versa.

Natural cracks formed inrocks due to the expansion of a rock

Exposed plutons due to pressure release

Weathering occurs faster at edges and corners of a block than on a flat face

– Increase surface area (physical)
– Dissolve minerals and cements (chemical)
– Alter hard minerals into soft minerals (chemical)

Soil forms through debris production, interaction with water, and interaction with organics. Produce unique layers, called horizons

Climate and Vegetation. Climate includes rainfall and temperature. Vegetation can add or remove material.

Loose, unconsolidated rock, mineral and glass fragments in the soil

Particles of broken rock are transported

Smallest sediments (ex. mud)

Made of lithified sediments (rock fragments from chemical or mechanical weathering)

Dissolved minerals crystallize out of solution (ex. Halite)

Made of calcite and silica-rich minerals (ex. Shells cemented together and Limestone)

Derived mostly from shells of organisms, most from the oceans, made of the carbonate mineral calcite

Plant remains (organic carbon) deposited in layers (ex. Coal and Oil Shale). Along ancient rivers and swamps.

Laying down of sediment carried by wind, flowing water, the sea or ice

-Transforms loose sediment into solid rock: burial increases pressure, squeezes out air and water, and compacts grains.
-Minerals (often quartz or calcite) precipitate from groundwater into pore spaces. This cement glues the loose sediments together
*Or-> Deposition, compaction, cementation

Clastic (ex. Breccia and Conglomerate)

Rounded rock clasts

-High velocity: sediments are eroded. Low velocity: sediments are deposited
-Well sorted means grains are all the same size. Poorly sorted is a mixture
-Faster waters can carry larger sediments

Form chemically, in water (ex. evaporites)

Created by ripple and dune migration. Can help you
determine information on the depositional environment

Tiny organisms that float in the ocean and their tests are deposited after death

Fine-grained limestone made of tiny plankton

Made from shells of silica-rich marine plankton (diatoms, radiolarians) deposited on deep seafloor (ex. Flint)

Any kind of rock changed from its original form (parent rock (protolith)). Through: heat, pressure, fluids

1. Occurs over wide areas, affects large volumes of rocks, and is associated with tectonic processes such as plate collision and crustal thickening (orogenic metamorphism) and ocean-floor spreading (ocean-floor metamorphism)
2. Increasing temp. and pressure
3. Foliated

-Deformation causing rock layers to bend and and have a curve through tectonic compression.
-Described by the geometry of the hinge.
▪ A nonplunging fold- has a horizontal hinge.
▪ A plunging fold- has a hinge that is tilted.

1. Rock minerals and texture are changed, mainly by heat, due to contact with magma
2. High temp, not as high pressure
3. Nonfoliated

Layering/parallel alignment of mineral crystals, often due to stress (ex. Slate, Phyllite, Schist, Gneiss). Non-foliated -> Quartzite, marble

1. Texture--interlocking crystals
2. Foliation--layering/parallel alignment
of mineral crystals
3. Minerals--presence of those that form
only through metamorphic processes (ex. garnet)

-Low grade (low temperatures and pressures)
-High grade (high temperatures and pressures)

Change in size and shape of minerals, but mineral type stays the same

Extremely high pressures and high temperatures caused by friction and transfer of energy

New minerals grow that differ from those in the protolith

P and S. P arrives first, then S
1. Travel by compressing and expanding the material
parallel to the wave-travel direction, traveling through solids, liquids, and gases.
2. Travel by moving material back and forth, perpendicular to the wave-travel direction. S-waves are slower than P-waves, and they travel only through solids, never liquids or gases.

L and R. L arrives first, then R
Surface waves travel along Earth's exterior and are the slowest and most destructive
1. L-waves (Love waves) move the ground back and forth like a writhing snake.
2. R-waves (Rayleigh waves) are P-waves that intersect the land surface. They cause the ground to ripple up and down like water.

A break in the rocks of Earth’s crust or mantle, along which rocks have moved past each other

Special kind of reverse fault that has a lower angle slope (dip). It’s a common fault compressional mountain belts

One block slides laterally past the other block. The fault itself is vertical, but motion is horizontal

Vibration of Earth produced by the rapid release of energy when rocks grind against each other (at a fault).
As seismic waves

Instruments that record ground motion.

P-wave and S-wave arrival times can be graphed. A travel-time curve plots the increasing delay in arrivals. The time gap yields distance to the epicenter.
1. Data from three or more stations pinpoints the epicenter.
2. The distance is drawn as a radius from each station, creating a circle of equidistant points.
3. Circles around three or more stations will intersect at a point. The point of intersection is the epicenter.

Measurement of the amount of energy transferred by a wave.

A measurement of size based on the maximum amplitude of seismograph waves OR amount of ground motion measured on a
seismograph

Severity of damage and human perception

Uses many seismic waves’ amplitudes, and the amount of displacement along the fault—most accurate

Unconsolidated soil and sediment that has a lot of water in it will liquefy due to the vibrations within the water (like quicksand)

Waves caused by undersea volcanoes, earthquakes, and landslides

Ground shaking, Ground lifting, Liquefaction, Tsunamis

Rock layers erode but match across valleys

States that mostsedimentary rocks are deposited in horizontal beds

Layers of rock are superimposed, or laid down one on top of another. The oldest rock strata will be on the bottom and the youngest at the top.

Atoms that have different #s of neutrons in the nucleus; materials that keep track of time
Parent isotopes (unstable)
Daughter isotopes (stable)

Helps to determine the reletive ages of rocks (sedimentary or igneous) that have been tilted or folded, or rocks (metamorphic or igneous) that wren't originally formed in horizontal layers (ex. Magma can cut through sedimentary rocks and form new rocks).

Return to their original shape and size

Causes rock to deform by flowing and folding; occurs at higher T and P conditions; does not return to their original shape

Occurs in the shallower crust; Results in rocks being broken apart, causing a loss of coherence; Rocks break by fracturing.

A fold that looks like an arch. The limbs dip out and away from the hinge.

Compression- takes place when an object is squeezed.
Tension- occurs when the ends of an object are pulled apart, which stretches and thins the material.
Shear- develops when surfaces slide past one another.
Pressure- occurs when an object feels the same stress on all sides.

A fold that opens upward like a trough. The limbs dip inward and toward the hinge.

Fractures filled with minerals

Processes that fault and fold rocks Rocks were originally horizontal – folded later

Basin- a fold shaped like an upright bowl.

Dome- a fold with the appearance of an overturned bowl.

The inclusions must have been formed before they became part of another rock,therefore must be older than the intrusion or sedimentary rocks that encloses them (ex. xenoliths).

Beds in a continous sequence

A contact indicating a gap in geologic record

Foms when rocks are titled or folded, eroded, and covered by younger horizontal strata

Form when a sequence of sedimentary rock is deposited and remins horizontal, undergoes erosion if sea level drops, and later is covered by new sedimentary rock when the rea is once again submerged