Test 1 Flashcards
Geocentric
Earth sits motionless at the center of the universe
Heliocentric
sun lies act the center of the universe
star
immense ball of plasma
Planet
object that orbits a star, is roughly spherical, and has “cleared its neighborhood of other objects”
terrestrial planets
consists of a shell of rock surrounding a ball of metal
moon
sizable body locked in orbit around a planet
Big bang theory
all matter and energy was initially packed into an infinitesimally small point
nebulae
patchy clouds of hydrogen and helium gas
accretionary disk
bulbous plate-like shape
protostar
when the ball of gasses becomes hot enough to glow
supernova
when stars run out of fuel, collapse, and explode
Planetesimals
bodies whose diameter exceeds 1 km
protoplanets
almost full sized planets
differentiation
In bodies whose temp rose sufficiently to cause internal melting, denser iron alloy separated out and sank to the center of the body, whereas the lighter rocky materials remade in a shell.
atmosphere
the envelope of gas that surrounds the planet
sections of the atmosphere by increasing altitude
Troposphere, stratosphere, mesosphere, thermosphere
Hydrosphere
oceans, surface water, and groundwater
Cyrosphere
ice
geosphere
solid Earth, from the surface to the center
Bathymetery
variations in depth of the seafloor
organic chemicals
carbon-containing compound the either occurs in living organisms or has characteristics that resemble compounds in living organisms
Minerals
a solid, natural substance, in which atoms are arranged in an orderly pattern
Glasses
a solid in which atoms are not arranged in an orderly pettern
Rocks
an aggregate of mineral crystals or grains, or a mass of natural glass
Greatest to least proportion of silica
Felsic, intermediate, mafic, and ultramafic
Biosphere
the aggregate of all living organisms, as well as the portion of Earth in which living organisms exist
When did differentiation of the Earth occur?
about 4.5 billion years ago
Till
sediment left behind by melting glaciers
paleomagnetism
a record of Earth’s magnetic field in the past
magnetic declination
the angle between the direction that a compass needle points and a line of longitude at a given location
magnetic inclination
the angle between a magnetic field line and the surface of the Earth
Mid ocean ridge fracture zones
narrow bands of vertical cracks and broken up rock
Seamounts
isolated submarine mountains, which were once volcanoes but no longer erupt
Magnetic anomaly
the difference between the expected strength of Earth’s main dipole field and the actual measured strength of the magnetic field
Asthenosphere
warmer mantle that can flow very slowly when acted on by a force
Continental lithosphere thickness
~150 km
oceanic lithosphere thickness
~100 km
Continental crust thickness
25-70 km
oceanic crust thickness
7-10 km
Wadati-Benioff zone
the band of earthquakes in a downing plate
Accretionary prism
sediment from the downing plate piles up at the boundary
Mantle plume
a column of very hot rock rising up through the mantle to the base of the lithosphere
rifting
when a continent splits apart
Suture
the boundary between once two separate continents after a collision
Polymorphs
two different minerals that have the same composition but different crystal structures
Biomineralization
when minerals grow at the interface between the physical and biological components of the Earth system
How does a crystal grow?
from the inside out so the outer most layer is the youngest part of the crystal
Color
results from the way a mineral interacts with light
Streak
the color of a powder produced by pulverizing the mineral
Luster
the way a mineral surface scatters light
Hardness
a measure of the relative ability of a mineral to resist scratching
Specific gravity
represents the density of a mineral
crystal habit
the shape of a single crystal with well formed crystal faces
Special properties
such as the whether a mineral reacts with a certain chemical
Cleavage
If a mineral breaks to form distinct planar surfaces that have a specific orientation in relation to the crystal structure
Conchoidal fractures
smoothly curving, clamshell-shaped surfaces
Independent tetrahedra
on oxygen shared
single chain
tetrahedra linked to form a chain by sharing two oxygen atoms
Double chains
share 2 or 3 oxygen atoms
sheet silicates
tetrahedra share 3 oxygen atoms and therefore form 2-D sheets
Framework silicates
each tetrahedra shares all 4 oxygen atoms forming a 3-D structure
Igneous rock
any rock formed by the solidifying of a melt
Extrusive igneous rock
rock that forms by the freezing of lava above ground, in contact with air or water, after it erupts
Pyroclastic debris
a rock made from cemented together fragments
Intrusive igneous rock
rock formed by the solidification of melt underground, after it has intruded into preexisting wall rock
Melting due to decompression
occurs when the mantle rock moves slowly for as the rock moves up its pressure lessens while the rocks temp remains the same
Assimilation
As magma sits underground before solidifying completely, it may incorporate chemicals dissolved from the wall rocks.
The two reasons that magma rises
buoyancy and pressure from the weight of overlying rock
Fractional crystallization
different minerals grow in sequence so the melt composition changes progressively as cooling takes place
Mafic lava characteristics
low viscosity
broad, thin flows
Volatile-rich celtic lavas
tend to erupt explosively and from thick ash and debris
Dike
a tabular intrusion that cuts across a pre-existing layering
Sill
a tabular incursion that injects between layers
Plutons
blob-shaped intrusions that range from tens of meters across to tens of km across
xenolith
a body of rock within an intrusion
Crystalline texture
size and visibility of individual crystals
Fragmental texture
from from pyroclastic debris and consist of chunks and/or shards that are packed together
Prophyritic rocks
- the melt cools slowly at depth forming larger crystals
2. the melt rises and erupts so that the remainder cools quickly forming smaller crystals
mafic rock color
tend to be black or dark gray
intermediate rock color
lighter gray or greenish gray
felsic rock color
light tan to pink or maroon
Pumice
a felsic volcanic rock that consists tiny air bubbles
Scoria
mafic volcanic rock with many air bubbles
Tuff
composed mostly of volcanic ash