| A | B |
|---|
| bedrock | unweathered rock that lies below the lowest layer of soil |
| humus | the decayed remains of plants and animals |
| soil | the loose material that covers much of Earth's surface |
| subsoil | the layer of soil just below the topsoil |
| topsoil | the uppermost layer of soil |
| delta | a large mass of deposited sediment at the mouth of a river |
| deposition | the dropping of sediment by wind, water, ice and gravity |
| erosion | the movement of weathered rock material from one place to another |
| glacier | a large mass of slow moving ice that flows down a slope |
| weathering | the slow breaking apart or wearing away of rock into smaller pieces |
| fossil | the preserved remains of a plant of an animal that lived long ago |
| Paleontologist | a scientist who studies fossils and organisms that lived long ago |
