1. Physical (Mechanical)
Frost Wedging
Salt Cracking
Bioerosion
Abrasion
Thermal expansion
Pressure Release
Chemical
Dissolution
Oxidation
Acid-Base
Organic

2. In the 1990’s several scientists (not geologists) suggested that the pattern of erosion on the base of the Sphinx required flowing water, making the Sphinx over 10,000 years old. What form of weathering, if any, could have produced this effect in a desert?
Acid rain B. Frost wedging C. Salt cracking D. Bioerosion
E. None would

3. 50% of soil is air and water
Leaching – from O and A
Accumulation – B
50% of soil is air and water
Organics in O are a balance between generation and decomposition
OM affects
Water retention
Soil compaction
Nutrient retention
Soil Color
Type of soil depends on
Bedrock
Climate – temp., rain, etc.
Vegetation
Time

5. In many South Florida soils there is very little O layer, despite the vegetation. Why?
Little leaching B. High temperature
C. Poor bedrock D. Water saturation

6. Soil and Farming
Excessive tilling and use of N fertilizers encourages soil bacteria to destroy OM
Removal of plant remains reduces OM addition
Leads to excessive fertilizer use and runoff – water contamination

7. Back yard – undisturbed since late 1960’s
Back yard – undisturbed since late 1960’s. Recently cleared of 2nd growth forest (Oak, Gum, Holly, Hickory, Magnolia).
A Tale of Two Soils
Front yard – scraped clean down to zone B in Covered with sod.