Harrodsburg--Glossary

Glossary

Technical words not found in this glossary can be found in geologic dictionaries such as the "Glossary of Geology," 4th edition, by Julia A. Jackson, published by the American Geological Institute.

Alluvium (al-lu´-vi-um): Unconsolidated (see below) sediments, typically clay, silt, sand, and gravel, deposited by a stream or river.

Bentonite (ben´-ton-ite): A special type of clay bed usually formed by alteration of a volcanic ash deposit.

Chert: A hard, dense form of silica commonly referred to as flint. When geologists use the term flint it is usually used to refer to the darker, more pure forms of chert.

Clay: As used here, this term refers to a deposit of extremely fine-grained (less than 1/of a millimeter) sediments. Clay particles are commonly either quartz or any one of a series of complex minerals called clay minerals.

Coal: A rock formed from the alteration of plant deposits (peat) by heat, pressure, and time.

Colluvium (col-lu´-vi-um): A loose deposit of soil, rock, and other sediment that usually forms along the base of cliffs and steep slopes. These deposits are usually formed by falling or sliding debris.

Concretion (con-cre´-tion): A hard, compact mass of a mineral concentration found within a rock. The mass is usually formed by the precipitation from water around a nucleus, such as a shell or bone, in a host rock. The most common in Kentucky are siderite concretions. A geode is an example of a concretion.

Conglomerate (con-glom´-er-ate): A sedimentary rock made up principally of rounded pebbles (usually with some sandstone between the pebbles).

Crossbed: A layer or bed of sediment that naturally occurs at an angle, as in a sand dune. Also spelled: cross-bed.

Dolomite (do´-lo-mite): A common sedimentary mineral composed of a calcium and magnesium carbonate; similar to the calcium carbonate mineral calcite, but with the addition of magnesium. Also refers to the sedimentary rock dominated by the mineral dolomite; this use of the word is synonymous with dolostone.

Fault: A surface or zone of surfaces separating two rock masses across which one mass has slid past the other.

Fluvial (flu´-vi-al) Deposits: Sediments deposited by a river or stream.

Formation: As used here, formation refers to the named sedimentary rock layers that are typically mapped (for example, Borden Formation). Formations are commonly subdivided into members and beds (e.g., Tanglewood Limestone Member of the Lexington Limestone). Several related formations may be combined to form a named group (for example, Breathitt Group).

Geode (ge´-ode): A mineral concentration, usually globular in form, that is typically hollow and internally lined with crystals.

Graben: A down-dropped block of crustal rock bounded by faults on either side.

Gravel: As used here, a sedimentary deposit composed of gravel-sized particles (> 2 mm) of rock.

Group: A named sedimentary unit or package composed typically of several named formations (see Formation above).

Interbedded: Alternating layers of different rock types; the layers are usually fairly thin.

Interlayered: Alternating layers of different rock types.

Ironstone: As used here, a bed or concretion dominated by the iron carbonate mineral siderite.

Karst: A landscape, usually with a limestone bedrock, dominated by sinkholes, caves, and natural underground drainage. Named after Karst, Yugoslavia. The shaded relief map to the right (Nicholasville area, Little Hickman 7.5-minute quadrangle) shows the dimpled landscape typical of karst terrain. Each dimple is a large sinkhole.

	Sinkhole seen from the eastern side of the Camp Nelson National Cemetery. Little Hickman 7.5-minute Quadrangle. 26 KB image, 162 KB image.
	Large sinkhole seen from the northern side of the Camp Nelson National Cemetery. All of foreground is sloping toward the sinkhole. Little Hickman 7.5-minute Quadrangle. 28 KB image, 175 KB image.

Limestone: A sedimentary rock composed largely of the calcium carbonate mineral calcite. Limestone is typically formed from the calcite cementation of sediment composed of grains commonly derived from broken-up sea shells and algae (also composed of calcite).

Matrix: As used here for sedimentary rocks, refers to the fine grains of silt or sand found between larger grains (e.g., sandstone matrix of a quartz-pebble conglomerate).

Member: A subdivision of a formation (see Formation).

Quartz: The most common crystalline mineral variety of silica and one of the most common minerals on the crust of the earth. Quartz is harder than steel and can scratch glass.

Quartzite: A sandstone composed almost entirely of sand-sized quartz grains.

Quartzose: Quartz rich.

Sand: A sediment composed of grains between 1/16 to 2mm; in other words, between silt and granule sizes.

Sandstone: A rock formed by the cementation of sand (excluding calcite sand).

Sediment: Mineral or organic grains (of any size) that are transported or deposited by air, water, or ice. As used here, it is an unconsolidated (see below) accumulation of these grains.

Shale: A fine-grained sedimentary rock composed of clay (and commonly silt) grains. The rock typically breaks into thin layers.

Silt: Sediment grains that range in size from 1/256 mm to 1/16 mm, or greater than clay size but less than sand size. The term also applies to an unconsolidated (see below) deposit of silt-sized particles.

Siltstone: A rock formed by the cementation of silt grains (excluding calcite silt).

Sinkhole: A depression in the surface of the Earth in an area with karst. At the surface it is commonly circular in shape and can measure meters or tens of meters in diameter. It drains below the surface and is commonly funnel-shaped.

Terrace Deposits: A bench-shaped deposit of unconsolidated (see below) sediments usually deposited when water levels were higher.

Tongue: A mapped rock layer that thins and disappears laterally.

Topography: The natural or physical features of a land surface or any part of the Earth's surface, including its relief and the position of its natural and man-made features.

Unconformable: As used here, the relationship between two adjacent rock layers where deposition was not continuous. It generally indicates a period of erosion before deposition of sediments over the older rock layer.

Unconsolidated: Sediment that has not been cemented; it is generally loose.