of Geology Terms
Terms not in this glossary might be found in the online geological dictionary at Iverson's WebRef.
alluvium-sediments deposited by a stream.
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.
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.
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.
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.
M.Y.A.-Million Years Ago
outwash-sand and gravel deposited by meltwaters streaming from the front of a glacier.
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.
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