Peta geologi

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Peta geologi
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• What is a geological map ?
• A geological map gives information on the
  superficial layers of the earths crust. The
  geological formations are listed according to
  their composition (lithology), their age
  (stratigraphy) and their structural position
  (tectonic). They are placed on a topographic base
  (map) using different graphic elements (symbols,
  figuratives and colors). The choice of scale
  depends on the geological content and the
  intended objective of the map.

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• A geologic map is an illustration of a huge
  volume of geologic information. Using a
  geological map, a geologist can show the
  distribution of rock bodies at the surface of the
  Earth and geologic structures which have deformed
  those rocks. Photo of Bright Angel quadrangle

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• Geological maps show the occurrence, nature,
  extent and stratigraphic age of rock strata in a
  district

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• How are geological maps made ?
• The essential condition for establishing a
  geological detail map is a precise field survey,
  based on numerous measurements and observations.
  The topographic base is generally taken from maps
  at a scale of 110'000, such as those of the
  comprehensive cadastral plans.
• The field geologist determines the rock type
  according to various criteria and measures its
  orientation. All data are transcribed onto the
  map and in a field notebook. Besides the natural
  or artificial outcrops, data from bore holes or
  important test holes are taken in consideration.
• In the case of a doubtful rock identification,
  complementary investigations are carried out in
  the laboratory on samples of these rocks.
• At the end of the field survey, the geologist
  establishes an original draft at a scale of
  125'000 and constructs some geological sections
  across the studied sector. He also writes an
  explanatory note that generally contains numerous
  illustrations.
• The geological cartography section assures the
  direction of the project, carries out the editing
  of the map, establishes the final legend of the
  map and provides indispensable data for the
  cartographers.

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Bright Angle Quadrangle
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