Week 8: Glacial geomorphological mapping Flashcards
Two sequential stages to glacial geomorphological mapping
- Morphological mapping
2. Geomorphological mapping
Morphological mapping =
Purely descriptive, should be objective
Recording outline shape of morphological features using break of slope/standard symbology
Recording high elevation crest-line of feature
Geomorphological mapping =
Interpretive and therefore subjective
Delimiting different landforms within a formational classification
e.g. moraines/drumlins/eskers
Usually based on breaks of slope
ISSUE:
- polygenetic landforms and equifinality
e. g. moraines/protalus ramparts/landslides
Esker =
sinuous looking ridge
Quantative data (of location/morphometry)
Location
Density
Spacing
Length
Width
Elongation
Orientation
Shape
Complications for accurate mapping
Cross-cutting/superimposed landforms (Clark 1993, 1994)
Azimuth biasing and shading (Smith and Clark 2005)
Postglacial modification
Superimposed landforms
Flutings/drumlins can be remoulded due to overprinting
Increases towards ice margin and decreases towards ice divide
Azimuth biasing and shading
Aerial photos can be affected by the shadow effect/sun angle etc
Postglacial modification
Anthropogenic activity
Erosion/deposition
Vegetation
Main approaches to mapping
- Aerial photographs
- In the field
- Satellite imagery
- Digital elevatio models
Using aerial photographs for mapping
Vertical/oblique i.e. not ground-based
Overlapping aerial photographs (stereo pairs) = 3D viewing with stereoscope
= digital elevation model
In the field mapping
Walking, viewing and traversing landforms from different directions
Best when sun low
GIS now allows multiple layer assessment including engineering properties etc
Surficial =
appear to be real until examined closely
