GEOLOGICAL MAPPING
What Is Geological Mapping?
Geological mapping is the systematic identification, measurement and interpretation of rocks, sediments, geological structures and surface materials within a defined area, followed by their representation on a map.
In simple terms, a geologist goes into the field and works out:
- What rocks are present?
- Where do different rock units occur?
- How are those units related to each other?
- What is the orientation of bedding, foliation or other structures?
- Where are faults, fractures, folds, dykes or veins?
- How deeply are the rocks weathered?
- What surface deposits cover the bedrock?
- What geological conditions could affect the proposed project?
The final geological map may show lithology, stratigraphy, geological contacts, faults, folds, fractures, lineaments, mineralized zones, superficial deposits and geomorphological features, depending on the purpose and scale of the investigation.
For example, a regional map may distinguish major formations across tens or hundreds of square kilometres. A detailed site investigation may instead concentrate on individual outcrops, fracture sets, weathering grades and geological contacts over a much smaller area.
The scale matters. So does the objective.
A map prepared for mineral exploration will ask different questions from one prepared for a tunnel, highway, groundwater investigation or landslide assessment.
Why Geological Mapping Matters
Geology influences almost every major decision involving the ground.
A proposed road may cross a fault zone. A quarry may contain an unexpected intrusive contact. A groundwater investigation may overlook a fractured-rock aquifer if the structural geology isn’t properly understood. A hillside that appears stable from a distance may contain unfavourably oriented discontinuities that become important during excavation.
These are the kinds of issues that field mapping can bring to the surface early.
Geological mapping therefore provides a geological framework for subsequent investigations such as geophysical surveys, drilling, geochemical sampling, geotechnical assessment and 3D geological modelling.
It doesn’t replace those investigations. It helps determine where they should be focused and and how their results should be interpreted.