- Geologic map
A geologic map or geological map is a special-purpose
mapmade to show geologicalfeatures.
The stratigraphic contour lines are drawn on the surface of a selected deep
stratum, so that they can show the topographic trends of the strata under the ground. It is not always possible to properly show this when the strata are extremely fractured, mixed, in some discontinuities, or where they are otherwise disturbed. Strike and dipsymbols consist of (at minimum) a long line, a number, and a short line which are used to indicate tilted beds. The long line is the strike line, which shows the true horizontal direction along the bed, the number is the dip or number of degrees of tilt above horizontal, and the short line is the dip line, which shows the direction of tilt.
The oldest preserved geologic map is the
Turin papyrus, made around 1150 BCE for golddeposits in Egypt.
A fascinating story of the first modern geologic map is told in "
The Map that Changed the World", by Simon Winchester. It's the story of William Smith, a canal digger who created the first geologic map of Great Britain in 1819, but ended up in debtor's prison and lived homeless for 10 years until he was recognized for his work by King William IV in 1831. (Harper-Collins publishers, 2202. ISBN 0-06-093180-9)
Maps and Mapping across the globe
United States, geologic maps are usually superimposed over a topographic map(and at times over other base maps) with the addition of a color mask with letter symbols to represent the kind of geologic unit. The color mask denotes the exposure of the immediate bedrock, even if obscured by soil or other cover. Each area of color denotes a geologic unit or particular rock formation (as more information is gathered new geologic units may be defined). However, in areas where the bedrock is overlain by a significantly thick unconsolidatedburden of till, terrace deposits, loessdeposits, or other important feature, these are shown instead. Stratigraphic contour lines, fault lines, strike and dip symbols, are represented with various symbols as indicated by the map key. Whereas topographic maps are produced by the United States Geological Surveyin conjunction with the states, geologic maps are usually produced by the individual states. There are almost no geologic map resources for some states, while a few states, such as Kentucky, are extensively mapped geologically.
since 1835; a separate Geological Survey of Northern Ireland (drawing on BGS staff) has operated since 1947.
Two 1:625,000 scale maps cover the basic geology for the UK. More detailed sheets are available at scales of 1:250,000, 1:50,000 and 1:10,000. The 1:625,000 and 1:250,000 scales show both onshore and offshore geology (the 1:250,000 series covers the entire UK
continental shelf), whilst other scales generally cover exposures on land only.
Sheets of all scales (though not for all areas) fall into two categories: :::Superficial deposit maps (previously known as "solid and drift" maps) show both bedrock "and" the deposits on top of it.:::Bedrock maps (previously known as "solid" maps) show the underlying rock, without superficial deposits.
The maps are superimposed over a topographic map base produced by
Ordnance Survey, and use symbols to represent fault lines, strike and dip or geological units, boreholes etc. Colors are used to represent different geological units. Explanatory booklets (memoirs) are produced for many sheets at the 1:50,000 scale.
Small scale thematic maps (1:1,000,000 to 1:100,000) are also produced covering
geochemistry, gravity anomaly, magnetic anomaly, groundwater, etc.
* [http://www2.nature.nps.gov/geology/usgsnps/gmap/gmap1.html Geologic Maps] " from USGS National Park Service"
* [http://ngmdb.usgs.gov/ USGS National Geologic Map Database]
Wikimedia Foundation. 2010.
Look at other dictionaries:
geologic map — geologic map, a map that shows by various signs, colors, and symbols the geological features of a region, including the structure, composition, and age of the materials below the surface … Useful english dictionary
Map — For other uses, see Map (disambiguation). A map is a visual representation of an area a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes. Many maps are static two dimensional,… … Wikipedia
Map projection — A medieval depiction of the Ecumene (1482, Johannes Schnitzer, engraver), constructed after the coordinates in Ptolemy s Geography and using his second map projection A map projection is any method of representing the surface of a sphere or other … Wikipedia
Map — /map/, n. Walter, c1140 1209?, Welsh ecclesiastic, poet, and satirist. Also, Mapes /mayps, may peez/. * * * I Graphic representation, drawn to scale and usually on a flat surface, of features usually geographic, geologic, or geopolitical of an… … Universalium
Geologic modelling — is the applied science of creating computerized representations of portions of the Earth s crust, especially oil and gas fields and groundwater aquifers. In the oil and gas industry, realistic geologic models are required as input to reservoir… … Wikipedia
map — mappable, adj. mapper, n. /map/, n., v., mapped, mapping. n. 1. a representation, usually on a flat surface, as of the features of an area of the earth or a portion of the heavens, showing them in their respective forms, sizes, and relationships… … Universalium
MAP — See modified American plan. * * * I Graphic representation, drawn to scale and usually on a flat surface, of features usually geographic, geologic, or geopolitical of an area of the Earth or of any celestial body. Globes are maps represented on… … Universalium
The Map that Changed the World — is a book by Simon Winchester. It tells the story of geologist William Smith and his great achievement, the first geologic map of England and Wales, the first geologic map in the worldFact|date=July 2008. Smith s pivotal insights were that each… … Wikipedia
Topographic map — A topographic map with contour lines … Wikipedia
Thematic map — Edmond Halley s New and Correct Chart Shewing the Variations of the Compass (1701), the first chart to show lines of equal magnetic variation. A thematic map is a type of map or chart especially designed to show a particular theme connected with… … Wikipedia