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chapter 8 and 9
| Term | Definition |
|---|---|
| geologists estimate that the Earth is _____ years old | 4.6 billion |
| the principle that geologic processes that occurred in the past can be explained by current geologic processes is called | uniformitarianism |
| layers of rock called _____ show the sequence of events that took place in the past. | strata |
| Even though all three classes of rock can form layers, the ones most commonly studied are | sedimentary |
| the boundary between two beds of rock is called | bedding plane |
| the principle that a sedimentary rock layer is older that the one above it is called the law of | superposition |
| the principle that a fault or intrusion is younger than the layers it cuts through is called the law of | original horizontaltity |
| The absolute age of a rock layer is its ____age | numeric |
| using the rate of _______to determine absolute age would be less accurate for a surface feature such as the Grand Canyon which is millions of years old. | erosion |
| In general, about 30 cm of sedimentary rock are _____over a period of 1,000 years. | deposited |
| Some sedimentary rock layers show annual layers called | varves |
| which layer (summer or winter) is composed of darker, finer grains? | winter layer |
| Atoms of the same element that have different numbers of neutrons are called | isotopes |
| The original radioactive isotope is called the _____isotope | parent |
| The half-life is the time required for half of a radioactive sample to break down by decay to form the ______ isotope | daughter |
| What is the half-life of uranium-238 | 4.5 billion years |
| the ages of wood, bones, shells, and other organic remains embedded in rock can be determined through _______ dating | carbon 14 |
| The scientific study of fossils is called | paleontology |
| Some insects become fossilized is hardened tree sap called | amber |
| Organisms buried in _____ do not decay, because bacteria do not survive such low temperatures. | frozen soil |
| when minerals in ground water percolate through buried organic matter, the result is a nearly perfect mineral replica of the object. This process is called _______( hint it often happens to wood) | petrification |
| A fossil residue of a leaf that makes a "shadow" on sedimentary rock is called a __________ | carbon films. |
| fossilized dung or waste is from an animal called a | coprolites |
| The stones from the digestive tracts or dinosaurs are called | gostroliths |
| fossilized tracks, borings or burrows are called _____fossils | trace |
| fossils that occur only in rock layers of particular geologic age are called ______ fossils | index |
| geologists also use these fossils (#29) to locate deposits of ____ | natural gas |
Created by:
sydneyspooner
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