of smaller pieces into a larger mass.
of light and radiation from the surface.
deposited by a stream.
currents-movement caused by the rising of less dense, hotter materials and
the concurrent sinking of more dense, cooler materials.
surface above the focus, or center of origin of an earthquake.
esker-a snake-like ridge of roughly stratified sand and
gravel formed by water flowing in or under a glacier.
input from the sun.
interglacial period-warmer, humid to temperate periods
occurring between episodes of ice cover.
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.
of the energy released by an earthquake.
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.
land areas of igneous rock; these are thought to have combined to form the
larger tectonic plates and continents.
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
period of mountain building
and gravel deposited by meltwaters streaming from the front of a glacier.
study of the Earth's past based on the orientation of magnetic crystals frozen
into igneous rocks.
which have similar landscape, geology, and subsequently, biota.
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.
striation-scratches left in
bedrock materials which have been abraded by glacial ice usually carrying a grit
of sand, gravel, and/or boulders.
zone-when two tectonic plates collide, the denser plate will dive under the
less dense one, being subducted.
front edge of a glacier, which may be either advancing or retreating
till-unsorted, unlayered drift
deposited directly by a glacier.
materials-loose sediments which have not been lithified (solidified) into