Test 2 Earth Science (ROCKS AND MINERALS GEOLOGIC)

Junior year semester 1

Mineral

must be found in nature (anything man made is not a mineral), must be solid, must be from nonliving things, must have a definite chemical composition.

Rock

any naturally occurring solid mass of mineral or mineral-like matter

Luster

appearance in reflected light

Color

can vary and is not as diagnostic

Streak

color of mineral in powdered form

Ability to transmit light

light can travel through a mineral causing it to be translucent or transparent

hardness

ability to resist scratching or abrasion

Cleavage

tendency to break along planes of weak bonding

Fracture

random pattern of breakage

Tenancy

resistance to cutting, breaking, bending, and deformation

Lithification

Conversion of sediments through compaction and crystallization by groundwater to form sedimentary rock

Metamorphism

Change due to high temperatures and pressures below ground to form metamorphic rock

Sediment

Solid particles produced through weathering

Weathering

Breakdown of a material at the Earth’s surface 

Magma

Crystallization above or below ground to form igneous rock

Stratigraphy

study of layered sedimentary rock

Nicholas Steno

•Hypothesized that objects were preserved when they sank to the bottom of a body of water and were covered up by sediment.

James Hutton

Hypothesized that it must take a very long time for processes (weathering and erosion) to produce any significant change in the shape of Earth’s surface (now called the uniformitarian model)

1st rule principle of original horizontality

Rocks get deposited on top of each other (horizontally)

2nd rule principle of superposition

rocks at the bottom of the stack are the oldest and the rocks at the top are the youngest

3rd rule principle of cross-cutting relationships

older rocks may be cut by younger rocks or other geologic features (ex. lava)

Fossils

•Evidence of past life preserved in rocks

•Fairly rapid burial in fine- grained sediment to cut off the three major agents of destruction

•Decay

•Dissolution/minerals are dissolved

•Disarticulation/incomplete

Actual preservation

original organism is preserved

Permineralization

when organism is buried and then elements in groundwater completely impregnates all spaces within the body

Molds and casts

original material of the organism dissolves and leaves a cavity in the surrounding rock

Carbonization

when organic tissues of an organism are compressed

Trace fossils

indirect evidence left behind by an organism

Paleontologists

geologists who study fossils

Relative Dating/Time

process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages

Absolute Dating/Time

assigning the specific time units to rock or other geologic events

Inclusion

any material—such as a mineral, rock fragment, gas bubble, or fluid—trapped inside a mineral, crystal, or host rock during or after its formation

Dike

older rock surrounded by younger igneous rocks

4th rule

principle of lateral continuity