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Science Q3 Sief
Term | Definition |
---|---|
Bedrock | The bottom layer of soil, made mostly of soild rock |
Topsoil | The top layer of soil, made in part from broken pieces of lower layers of rock |
Physical weathering | caused by wind, water, plants, and ice |
Chemical weathering | It occurs when chemicals break up rocks by dissolving parts of them |
Fossils: | Any naturally preserved evidence of past life |
Mold: | An impression of an organism formed when sediment hardens around the organism . |
Cast: | A fossil of an organism formed when sediment fills a mold and hardens. |
Fossil fuel: | An energy-‐rich resource formed from the buried remains of once-‐living organisms. |
Index fossil: | A fossil of a type of organism that lived in many places during a relatively short time span. |
Mass extinction: | A period during which a large number of species become extinct. |