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8th Grade Fossils
Fossils
| Term | Definition |
|---|---|
| Erosion | The process by which the surface of the earth is worn away by the action of water, glaciers, winds, waves, etc. |
| Mold fossil | Forms when sediments bury an organism and sediments change into rock; the organism decays leaving a cavity in the shape of the organism |
| Cast fossil | Forms when a hollow cavity is filled with sand or mud that hardens into the shape of the organism |
| Petrified (mineralized) fossil | Forms when minerals soak into the buried remains, replacing the remains, and changing them into rock |
| Preserved fossil | Forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar or amber |
| Carbonized fossil | Forms when organisms or parts are pressed between layers of soft mud or clay that hardens squeezing almost the entire decaying organism away leaving the carbon imprint in the rock. |
| Trace fossil | Forms when the mud or sand hardens to stone where a footprint, trail, or burrow of an organism was left behind |
| Geologic time scale | A system of chronological measurement used by geologists, paleontologists, and other earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history. |
| Igneous intrusion | The action or process of forcing a body rock between or through existing formations, without reaching the surface |
| Index fossil | A widely distributed fossil, of narrow range in time, used in determining the relative age of related formations. |
| Igneous extrusion | A volcanic rock formation in which hot magma from inside the Earth flows out onto the surface as lava or explodes violently into the atmosphere |
| Fossil | Any remains, impression, or trace of a living thing of a former geologic age, as a skeleton, footprint, etc. |
| Unconformity | A disruption in rock sequence indicating interruption of sedimentation, commonly accompanied by erosion of rocks below the break. |
| Sedimentation | The deposition or accumulation of sediment |
| Evolution | The process by which a species (biological) or feature on Earth (geological) change over time |
| Relative age | This is used in geology to determine the approximate age of a rock, fossil, or other mineral; determined by comparing them to the known ages of rocks, fossils, and minerals around it. |
| Absolute age | The age of a rock or actual remains of an organism as determined by the measurement of radioactive decay from the time of the rock's formation or from the time of death of the organism |
| Igneous rock | Rock that forms when melted rock cools and hardens |
| Fault | A break, or crack, in Earth’s surface along which movement occurs |
| Half-life | The time required for one half the atoms of a given amount of a radioactive substance to decay |
| Law of superposition | The principle that in undisturbed rock layers, older layers of rock are underneath younger rock layers |
| Radiometric/radioactive dating | A way of measuring the age of a material by comparing the amount of a radioactive element with the amount of its decay element |
| Sedimentary rock | Rock that forms from compacted sediment |
Created by:
preese