1. Week Fifteen Synopsis of Ch. 14:
Soils: RS plays a limited role in the ID, inventory, & mapping of soils.
Rocks & minerals: Emphasis is placed on understanding unique absorption bands associated with specific types of rocks & minerals using imaging spectroscopy
Geology & geomorphology: RS can be used to extract geologic information including, structure, drainage patterns, & landforms

2. Soil Soils require in situ examination
Soil RS works in ideal situations only
Spectral reflectance characteristics via:
Aerial photography
Multispectral
Hyperspectral
A function of several characteristics:
Soil texture (% sand, silt, clay)
Soil moisture (dry, moist, saturated)
Organic matter content
Fe2O3 content
Soil salinity
Surface roughness

3. Soil: Texture and Moisture
Increasing reflectance with increasing wavelength visible through middle-infrared

4. Soil: Texture and Moisture
Smaller particles hold water better than larger ones (clay, silt, sand)
As such, more water means more absorption and less reflectance

5. Soil: Texture and Moisture
Higher moisture content in (a) sandy and (b) clayey soil results in decreased reflectance, especially in the water absorption bands (1.4,1.9, 2.7 μm).
Question: Why are water absorption bands more active in clayey soil?
1.4, 1.9, 2.7 water absorption bands

6. Soil: Texture and Moisture
More organics at surface means more absorption and lower spectral reflectance

7. Soil: Texture and Moisture
Active radar
24 cm (L band) radar:
> In dry sand can penetrate 1 – 2 m
> Can penetrate thin moist sand
5 – 8 cm (C band) radar:
> Can see extent of dry sand well

8. Soil: Organic Matter and Biological Soil Crusts
Moss, algae, lichen, bare ground
Fig. 14.9
Fig. 14.0

9. Soil: More… Iron oxide (Fig. 14-11). Salinity (Fig. 14-12)
High reflectance in red
Salinity (Fig )
More salt, more reflectance
Can be confused with silty soils
Surface roughness with radar
Must be dry and devoid of veg.
Sand = bright; clayey = dark
Meshing of wavelength to clast size means more reflectance
Fig. 14.9
Fig. 14.0

10. Rocks and Minerals: Imaging Spectroscopy
Imaging spectrometers are ideal
Optical properties vary in complex ways with wavelength
> electronic absorption processes (unfilled electron shells)
> crystal lattice vibration absorption processes
Often, hyperspectral sensors are needed
Refer to a spectral reflectance library
> JPL’s Salisbury et al > USGS Digital Spectral Library

11. Rocks and Minerals: Imaging Spectroscopy
Many diagnostics for mineral ID are found in thermal infrared
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on Terra has:
Band 6 for clay and hydrothermal discrimination
Bands 8, 14 for carbonate discrimination
Bands 10, 11, 12 for sulfates and silica

12. Geology: Lithology and Structure
Focus on image interpretation (shape, pattern)
Digitizing to characterize morphometric parameters (Table 14-1, pg. 525)

13. Geomorphology Sensors: Digital products: Aerial photography Radar
Lidar
Sonar
Digital products:
2.X dimensional interactive image
Oblique views
Image draping

14. Geomorphology Geomorphometry: Application areas:
Concave and convex slopes, curvature, flow accumulation, channel delineation, watershed partitioning, roughness
More here and here
Application areas:
Tectonic geomorphology
Subsidence and uplift
Paleoglacial studies
Coastal processes (hurricane erosion)
Landform evolution theories
Flood and other hazards mapping
River migration (border issues)