| A | B |
|---|
| The agent of mechanical weathering in which rock is worn away by the grinding action of other rocks | abrasion |
| Ice wedging causes mechanical weathering or rock by means of | freezing and thawing of water |
| What kind of weathering causes the mineral composition of rocks to change | chemical weathering |
| A rock containing iron becomes soft and crumbly and reddish-brown in color. It probably has been chemically weathered by | oxygen |
| A hot and wet climate causes weatering to take place | rapidly |
| Soil formation begins with the weathering of | bedrock |
| Soil that is rick in humus has high | fertility |
| When earthworms add their wastes to the soil, then die and decay in the soil, they are contributing to the formation of | humus |
| Living organisms in soil help to | mix the soil and make humus. |
| Decomposers are the soil organisms that | break down and digest the remains of dead organisms |
| Soil is valuable resource because it | is needed for plants to grow. |
| How long did it take for the thick, fertile soil of the North American prairies to develop | Thousands of years |
| The growth of plant ro animal activity may result in | mechanical weathering |
| Most of the work of mixing humus within the soil is done by | earthworms |
| Geologists infer from the rounded, eroded shapes of the Appalachian Mtns that | the mountains are made of soft rock |
