Maps and geological mapping

Maps and Geological Mapping

Types of Maps

  • Topographic maps: These depict the three-dimensional shape of the world (relief) in two dimensions using contour lines. Important for understanding the terrain and the overall geological setting.
  • Geological maps: Created out of topographic maps, these incorporate geological data, allowing geologists to understand the underlying rocks, structures, and age relationships.
  • Seismic maps: Used in oil and gas industries, these maps depict the subsurface structure of a location based on data from seismic exploration.
  • Aerial Photographs and Satellite Images: These provide real-world, bird’s-eye-views of the landscape and can be especially helpful when doing reconnaissance for a field trip.

Components of Maps

  • Scale: Indicating the ratio of a distance on the map to the corresponding distance on the ground.
  • Grid references: Used to locate specific points on the map.
  • Legend: Explains the symbols used on the map, it’s crucial to understand the geological features represented.

Geological Mapping

  • The process of creating a geological map involves fieldwork, observation, and interpretation. It is an essential skill in geology.
  • Fieldwork: This involves collecting data directly from rock exposures in the field. Tools such as a compass clinometer may be used to measure the strike and dip of rock layers.
  • Observation: Features to be observed and recorded in the field include rock type, structure (folds, faults, joints), and fossil content.
  • Interpretation: These observations are then combined to create a detailed map, from which the geological history of an area can be interpreted.

Mapping Techniques

  • Stereographic projection: A method of plotting geological 3D data in two dimensions. Useful for interpreting structural geology and understanding landforms.
  • Geographic Information Systems (GIS): Computer systems that can store, analyze, and visualize geographic data and help in accurate geological mapping.
  • Remote Sensing: Utilising technologies such as satellite imaging and LIDAR to gather data about the Earth’s surface. Increasingly important in modern geological work.