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Relative Dating
Question | A |
---|---|
older on the bottom, younger on the top | law of superposition |
the age of a fossil/rock layer compared to the age of the fossils/rock layers around it | relative age |
the exact age of a fossil as determined by radio active decay | absolute dating |
occurs when magma forces its way up into existing rock layers and hardens and cools before reaching the ground | intrusion |
a lava flow covers the top of an existing rock layer | extrusion |
a crack in the Earth that is always younger than the rock layers it cuts through | fault |
a gap in the geologic rock record | unconformity |
a fossil used to date other fossils - lived a short time, abundant and geologically widespread | index fossil |
water fossils | aquatic |
traces or evidence of once living organisms | fossil |
the type of rock where fossils are usually found (formed by compression and cementation) | sedimentary rock |