accretion-coalescence
of smaller pieces into a larger mass.
albido-reflectivity
of light and radiation from the surface.
alluvium-sediments
deposited by a stream.
B.Y.A.-Billion
Years Ago.
convection
currents-movement caused by the rising of less dense, hotter materials and
the concurrent sinking of more dense, cooler materials.
epicenter-land
surface above the focus, or center of origin of an earthquake.
drift-glacial deposits.
esker-a snake-like ridge of roughly stratified sand and
gravel formed by water flowing in or under a glacier.
insolation-radiant
input from the sun.
interglacial period-warmer, humid to temperate periods
occurring between episodes of ice cover.
isostatic rebound-"bouncing
back" of the mantle (and the crust atop it) following the removal of
weight. The weight of thousands of feet of glacial ice would have
depressed the plastic magma of the mantle. When the ice weight was
removed, the magma rebounds.
kame-a mound or
short ridge of stratified sand and gravel deposited by water streaming under or
trapped within glacial ice.
magma-semimolten
rock.
magnitude-a measure
of the energy released by an earthquake.
mechanical weathering-the
process by which rock is broken down into smaller fragments as result of
physical forces; for example, water may seep into cracks in rocks, freeze
and expand, thus breaking up the rock.
microplate-small
land areas of igneous rock; these are thought to have combined to form the
larger tectonic plates and continents.
Milankovitch
cycles-Long
period cycles in three orbital parameters that greatly influence Earth's climate,
discovered by the Serbian mathematician Milutin Milankovitch. This says
that long term variations in Earth's orbital properties (axial tilt and
eccentricity of orbit) influence climate by changing the seasonal and
latitudinal distribution of incoming solar radiation.
Modified Mercalli Intensity Scale-a system for measuring the intensity of
an earthquake based on observation of its effects on an area, e.g., damage to
structures.
M.Y.A.-Million
Years Ago
orogeny-a
period of mountain building
outwash-sand
and gravel deposited by meltwaters streaming from the front of a glacier.
paleomagnetism-the
study of the Earth's past based on the orientation of magnetic crystals frozen
into igneous rocks.
physiographic province-areas
which have similar landscape, geology, and subsequently, biota.
Pre-Cambrian-a
collective term for the time in Earth history before abundant fossils
existed. Comprising nearly 4 billion years, it includes the vast majority
of Earth history, under the headings of the Pre-Archean (4.5-3.8 BYA), Archean
(3.8-2.5 BYA), and Proterozoic (2.5-0.57 BYA) eons.
Richter scale-A logarithmic scale
measuring the amount of energy released during an earthquake on the basis
of the amplitude of the highest peak recorded on a seismogram. Each unit
represents a 10-fold increase in the amplitude recorded on the seismogram and a
30-fold increase in energy released by the earthquake.
stratified-layered
striation-scratches left in
bedrock materials which have been abraded by glacial ice usually carrying a grit
of sand, gravel, and/or boulders.
subduction
zone-when two tectonic plates collide, the denser plate will dive under the
less dense one, being subducted.
terminus-the
front edge of a glacier, which may be either advancing or retreating
till-unsorted, unlayered drift
deposited directly by a glacier.
unconsolidated
materials-loose sediments which have not been lithified (solidified) into
rock.
