STUDY GUIDE: CH.12 WEATHERING, SOIL, EROSION and the PROVINCES OF VA
1. What is weathering? The
breakup of rock
2. What is chemical weathering? The process
3. What is mechanical weathering? Breaking
by which rocks are decomposed, dissolved or loosened
rock into smaller pieces
4. How does temperature change cause weathering?
Water seeps into cracks in the rock. Over time, repeated freezing & thawing, or wetting & drying,
expands the crack, breaking the rock apart
5. What is abrasion?
Wind-blown sand or moving water rubs against the rock, wearing away or breaking off pieces of rock
6. What happens to the shape of a rock when it is abraded by water?
The longer a rock is abraded by water, the rounder & smoother it will be.
7. What evidence does glacial abrasion leave behind? Scratches
in rock call striations
8. What is exfoliation?
When rock is uplifted to the surface, there is less pressure on the rock so it expands in layers & pieces
break off
9. What type of weathering is ice wedging? Mechanical
10. What is hydrolysis? When
What type of weathering is from Plants/Animals? Mechanical
rocks react with water
11. What is oxidation?
When iron-bearing minerals in rocks react with oxygen to form reddish or yellow “rust.”
12. How does surface exposure affect the rate of weathering?
Weathering takes place on the surface. The more surface is exposed, the faster it will weather
13. How does mineral composition affect the rate of weathering?
Some minerals are more resistant to weathering than others
14. How does climate affect the rate of weathering? Warm & wet
climates speed up weathering
15. The arrow in the diagram below is pointing to a valley. Explain how the valley formed.
Because each rock has a different mineral composition, surface area or climate, they can weather at
different rates.
16. What is the process that describes how weathered materials are moved from one place to another? Erosion
17. What force is involved in all mass movements? Gravity
(Think… All types of Mass Movements or Mass Erosion consist of material moving downhill.)
18. What is a sudden motion of soil and rock?
Landslide
19. What are the agents of erosion (what transports the weathered material)?
20. What is a slow, imperceptible motion soil? Creep
21. What occurs when blocks of land tilt and slide along a curved surface? Slump
22. What is a sudden motion of water-filled clay and silt down hill? Mudflow
23. What factors control the development of soils?
Living Organisms, Topography, Climate (Temperature and amount of precipitation), Parent Material
24. How is bedrock changed to soil? Weathering
25. What affects the thickness of soil? Climate (Temperature and
amount of precipitation)
26. Layers in the soil are known as horizons
27. Soil is a mixture of weathered rock and decayed
organic material
28. The parent material of soil is the bedrock
29. Leaching of minerals occurs mainly in horizon B
30. Which horizon is the least evolved (weathered)? C
31. Where does the organic matter in soil come from? Decaying
plants and animals
32. What is located beneath soil layers? Bedrock
33-36. In the soil profile below, name and describe what is in each horizon.
A/O - topsoil - organic layer, made mostly of leaf matter & humus.
B - subsoil; red or brown color from iron oxides; made of clay & sand.
“leached zone” - minerals are washed down from above
C - slightly weathered bedrock
Bedrock or “Parent Rock”– solid rock beneath soil
37. In the map of Virginia below, label the name of each province.
Valley and Ridge
Coastal Plain
Appalachian Plateau
Piedmont
Blue Ridge
38-42. Describe the topography and what resources we can find in each province.
Coastal Plain –
Flat area composed of young, unconsolidated sediments that were recently deposited. Many oceans
fossils are found here.
Piedmont –
Area of rolling hills made by mostly metamorphic rocks. Slate, Sandstone, & Gold found here along with
Dinosaur fossils.
Blue Ridge –
A high ridge composed of very old igneous and metamorphic rocks. Beautiful views draw in tourists.
Valley and Ridge –
An area with long parallel ridges and valleys made by folded sedimentary rocks. Caves and Karst
Topography found in the limestone valleys.
Appalachian Plateau –
An area made by flat-lying sedimentary rocks, containing most of Virginia’s coal and petroleum
resources.
43. Between which two provinces would you find the Fall Line? Between
the Coastal Plain and Piedmont
44. Why do rivers form waterfalls when the pass over the Fall Line?
Rivers form waterfalls as they move from the tough rocks of the Piedmont to softer, more easily eroded
rocks of the coastal plain.
45. Which region would you find Karst Topography? Valley
and Ridge. What is Karst?
Karst Topography are areas with many caves and sinkholes. Karst occurs in areas with limestone
bedrock which dissolves easily in water.