Physical Geology Chapter 9
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50 terms
Terms | Definitions |
|---|---|
 Law of Superposition | *Developed by Steno in 1669 *Oldest rock on the bottom |
| Principle of Original Horizontality | *Layers of sediment are generally deposited in horizontal position *Rock layers that are flat |
| Principle of Cross Cutting | Younger cuts through old |
| Inclusion | *A piece of rock that is enclosed within another rock *Rock containing inclusion is younger |
| Unconformity | *Break in rock record produced by erosion/non deposition of rock units |
| Angular Unconformity | Tilted rocks are overlain by flat lying rocks |
| Disconformity | Strata on either side of unconformity are parallel |
| Nonconformity | Metamorphic/Igneous in contact with sediment strata |
| Paleontology | *Study of fossils *Reamins are now preserved in rocks gen. in sediment |
| Types of Fossils | *Remains of recent organisms (teeth) *Entire animal, flesh included *Petrified *Molds and Casts |
| Permineralization | *Mineral grow in cells of organisms remains *Cell wall remain intact (silica, pyrite, and carbonate) |
| Impressions | *Left by the bones-- Internal structure *Result of compression |
| Mold | Hollow imprint left by organism |
| Cast | Replica of organism |
| Carbonization | Remains smashed causing disassembly |
| Conditions for Favoring Preservation | *Rapid Burial *Possession of hard parts |
| Correlation | Match rocks of similar age in different regions- rely on fossils |
| Principle of Fossil Succession | Fossil organisms succeed one another in a definite and determinable order. Therefore, any time period can be recognized by its fossil content. |
| Index Fossil | Geographically widespread fossil limited to short span of geologic time |
| Proton | Positive charge |
| Neutron | Neutral |
| Electron | Negative charge |
| Atomic Number | *Elements identifying number *Equal to number of protons |
| Mass Number | Sum of number of protons and neutrons |
| Isotope | *Variant of same parent atom *Differs in number of neutrons *Different mass number of parent |
| Radioactivity | Spontaneous changes in structure of nucleus |
| Beta Emission | *Electron (beta particle) ejected from nucleus *Mass number unchanged *Atomic number increased by 1 |
| Alpha Emission | *Emission of 2 protons and 2 neutrons *Mass number is reduced by 4 *Atomic number 2 less |
| Electron Capture | Electron captured by nucleus and combine w proton to form neutron-Mass # unchanged, Atomic # minus 1 |
| Parent | Unstable radioactive isotope |
| Daughter | Result from decay of parent |
| Half Life | Time needed for half sample to decay--size does NOT matter |
| Radiometric Dating | *Percentage of radioactive atoms that decay during half is always the same *Compare ratio of parent to daughter |
| Sources of Error | *Closed system required *Want fresh, unweathered samples--igneous |
| Geologic Time Scale | *Adam S and Roderick M named Cambrian, Silurian, and Devonian *Had fight |
| Charles Lapworth | Added Ordovician |
| Eon | Greatest expanse of time Phanerozoic, Proterozoic, Archean, Hadean |
| Phanerozoic | Visible life, most recent eon |
| Proterozoic | Tiny fossils |
| Hadean | Oldest Eons |
| Era | Subdivision of an eon Cenozoic, Mesozoic, Paleozoic |
| Cenozoic | Recent Life |
| Mesozoic | Middle life |
| Paleozoic | Ancient life |
| Eras are subdivided into | Period |
| Period divided into | Epochs |
| Precambrian | Nearly 4 billion years before cambrian Not divided into smaller units b/c details unknown |
| Big Bang Theory | 13.7 by a Debris condensed and cooled down Genesis 1 |
| Nuclear Fusion | Nuclei join together, form one heavy nucleus Release energy in form of heat |
| Supernova | Death of very large stars |
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