Physical Geology - Exam 2

Weathering is the breakdown of rocks while erosion is the removal from its location

Physical weathering and chemical weathering

mechanical weathering breaks down rocks into smaller pieces with greater surface area.

• differential weathering

• rounding

• weathered surface on a rock

• pressure release

• frost wedging

• plant growth

• animal burrowing

• thermal cycles

• salt growth

exfoliation

smallest assemblies of matter

positively charged particles

negatively charged particles

an atom that has an excess or deficiency of electrons in the outer shell relative to number of protons in the neucleus

positively charged ions

negatively charged ions

• oxygen

• acids

give off large quantities of hydrogen ions (H+)

give off low quantities of hydrogen ions (H+)

With water→limonite

without water→hematite

kaolinite (clay mineral)

ions in solution

Fission a nuclear reaction in which an atomic nucleus

an accumulation of loose grains

the phase of lithification in which cement, consisting of minerals that precipitate from ground water, partially or completely fills the spaces between clasts and attaches each grain to its neighbor

the transformation of loose sediment into solid rock through compaction and cementation

consisting of cemented-together detritus derived from the weathering of pre-existing rock: produced from eroded mineral grains

produced directly by accumulation of organic remains of plants or animals

produced by precipitation of dissolved ions in water

1. gravel-sized grains

2. sand-sized grains

3. silt-sized grains

4. clay-sized grains

a shift to a tighter packing of the grains due to increasing overburden

precipitation of minerals from solution

• rounding: grains display more rounding further from the source

• sorting: sediment grains are separated according to size and shape. sediment sizes decrease with increased transport distance

where two different types of rock touch each other

• slaty foliation → metamorphism

• schistose foliation → more heat and/or pressure

• gneissic foliation → temperature change

• high pressure

• differential stress

• results in foliated texture

• occur in wide temperature range

• precipitated from or altered by hot water

• metasomatism: water adds new atoms to the rock

produces migmatites: exhibit both intrusive igneous and foliated metamorphic textures

produced by rapid application of extreme pressure

due to proximity to or contact with an igneous intrusion

a metamorphic rock re-crystallizes into a higher-grade metamorphic rock

shale→slate→phyllite→schist→gneiss→migmatite→granite

original rock before metamorphism

determining the absolute age of an igneous rock through its radioactive elements

an element with the same number of protons but different number of neutrons

same atomic number, different atomic mass

the spontaneous nuclear loss or gain of protons or neutrons at a constant and measurable rate

the original isotope before radioactive decay

the product of radioactive decay

the time required for half of the parent isotopes to decay into daughter isotopes

daughter nucleus has atomic number 2 less and mass number 4 less than parent nucleus

daughter nucleus has atomic number 1 higher than parent nucleus. no change in mass number

daughter nucleus has atomic number 1 lower than parent nucleus. no change in mass number

it is consistent

the temperature of an igneous melt at which it becomes a closed system

melt is sealed off so neither parent or daughter isotopes can leave

has different closure temperatures

Carbon-14

5,730 years

40,000 years

paleontology

an unconformity between parallel layers of sedimentary rocks which represents a period of erosion or non-deposition

the contact surface between younger sedimentary beds and eroded older intrusive igneous or metamorphic rocks

contact between rock layers where the lower, underlying rocks are tilted and the younger, overlying rocks are flat

beds that are deposited in deep, calm water formed horizontal or near horizontal layers

in a sequence of undisturbed beds, the oldest is at the bottom and the the beds get progressively younger and upward

sedimentary or volcanic layers extend laterally until it tapers out or hits an obstruction

any clast that has become included into another rock must be older than the rock into which it has been incorporated

any geologic feature that cuts across another geologic feature must be younger than that which it cuts through

sequence of sedimentary rock with complete record of depositional history

erosional contact between rock layers that represent a gap in geologic time (lost time)

a fossil used to date a geologic structure

• short geologic timespan

• broad geographic range

features found within sedimentary rocks that form during or after deposition but before lithification

features that result from the deformation of the earth’s crust after lithification

forces push the rock together from opposite directions

forces pulling away from each other in opposite directions

stresses act parallel to a plane

deformed material that recovers its original shape after stress is reduced or removed

material will bend while under stress but will NOT return to its original shape after stress is removed

material fractures at stresses higher than the strength of the material

a line formed by the intersection of an inclined bedding plane with a horizontal plane perpendicular to the dip direction

• angle: how many degrees off due north

• direction: what direction off of due north

angle that a bedding plane dips below the earth’s surface

• angle: number of degrees

• direction: compass direction the bed dips

• folds shaped like an arch

• oldest rocks in center of the fold getting progressively younger toward the edge

• bed dips away from hinge line

• fold shaped like a trough

• youngest rock are in the core of the fold and get progressively older toward the edge

• rock beds dip toward the hinge line

• folds in which the bed dips away from a center point

• oldest rocks are exposed at the core and get progressively younger toward the edge

• folds in which the beds dip toward a center point

• youngest rocks are exposed at the core

movement is parallel to dip direction

• hanging wall down relative to foot wall

• tensional stress

• hanging wall moves up relative to the foot wall

• compressional stress

• movement is parallel to the strike of the fault

• horizontal or lateral faults

• shear stress

If the block opposite an observer looking across the fault moves to the right

If the block opposite an observer looking across the fault moves to the left

dip-slip and strike-slip components of movement

• fault-zone

• slickensides

• drag folds

zone of broken rock that was ground up by fault movement

polished and striated rock surface

minor folds produced by movement