Understand✤ Soil is made of weathered rock and organic material.✤ Climate and other factors affect the composition of soils.
Do✤ Explain how soil forms.✤ Describe soil composition and the factors that affect it.
A-horizonResidual Transported (topsoil) soil soil B-horizon C-horizon Parent Proﬁle of material mature soils Soil Arctic Type Desert Temperate Tropical
Name four factors that affect soilcomposition. ✤ Time; parent material; topography; climate
12.2 #1. Describe the difference between aresidual soil and a transported soil. ✤ 12.2 #1. Residual soils form from the bedrock beneath it. Transported soil forms from parent material that originated in a different location.
#2. Sketch a soil profile andlabel A-, B-, and C- horizons.Describe what you are likelyto find in each horizon.✤ #2. A-horizon- is likely to contain humus and sand.✤ B-horizon is likely to contain iron oxides, clay and soluble minerals such as calcium and magnesium.✤ C-horizon- is likely to contain slightly weathered parent material.
#3. What rock materials are found insoil? ✤ #3. Sand, silt, and clay
#4. How does the amount of rainfall appear to affectwhether a soil is a grassland or a forest soil? Explain yourthinking. ✤ #4. It takes more rain to support a forest than it does to support grassland, thus, forest soil exists where there is more rain.
#5. How do you think the type of soil found in aparticular region might affect the lives of people inthe region? ✤ #5. The type of soil affects how easily crops can be grown and thus how large a population can be supported by local food growth.