Geology Dictionary

Geological Terms Beginning With "K"

Geological Terms Beginning With "K"


Surface deposits in the form of mounds, hummocks or ridges that are composed of stratified glacial sediments. These were deposited on, under or within glacial ice and then were left behind as positive relief features when the ice melted.


A common clay mineral with a chemical composition of Al2Si2O5(OH)4. Unlike many other clays it does not change dimensions under different moisture conditions and does not exchange ions with adjacent liquids. It is used as a whitening agent, antistick agent, extender and filler in many manufactured products including paper, paint, ceramics, toothpaste, cosmetics, rubber, and many other products.


A measure of the fineness of gold. It is used to represent the proportion of gold in an alloy. Pure gold is 24 carat gold. An alloy that consists of 50% gold and 50% other metals is 12 carat gold or 12/24 gold.


A landscape that is characterized by the features of solution weathering and erosion in the subsurface. These features include caves, sinkholes, disappearing streams and subsurface drainage. The image is a Landsat view of the area around Winter Haven, Florida. The round black features are lakes that have developed in sinkholes formed in the limestone bedrock. The width of this view is approximately six miles.


Solid organic substances frequently found in shales that can yield gases and liquids through heating. The organic component of an oil shale. The photo is a microscopic view of an organic black shale in reflected light the brown resinous material is kerogen.


A depression formed in glacial deposits when a buried block of ice, left behind by a retreating glacier and buried by sediments, melts to form a depression. These depressions are often filled with water to form a "kettle lake". The images shows a number of kettles and kettle lakes formed in the Bering Glacier's piedmont lobe. The largest kettle in the view is about 150 feet in diameter.


A potassium feldspar such as orthoclase, microcline, sanidine or adularia. Also referred to as potash feldspar. The two pink specimens in the photo are orthoclase.


A unit of pressure equal to 1000 bars or 14,500 pounds per square inch.


A variety of peridotite that is found in volcanic pipes which are thought to be intrusions from the upper mantle. Many diamond deposits are found in kimberlite pipes.

Kimberlite Pipe

A vertical structure beneath the site of a volcanic eruption, which was formed when rock material and magma from a mantle-source eruption passed upwards through the crust and erupted through the surface. It is often filled with brecciated volcanic rock which might include kimberlite or lamproite


An abrupt change in slope. A point on a stream profile where a change in gradient occurs. This could be caused by a change in underlying bedrock or bedrock structure. The photo shows a subtle knickpoint in eastern Nebraska.


A small hilltop that is round in shape.


A metamorphic mineral that occurs in beautiful hues of blue and green. It has perfect cleavage and has a hardness of 4.5 in one direction, 5.5 in another, making it best used in items that will not be subjected to wear.