| Term | Definition |
|---|
| law of superposition | is used to establish the relative age of a rock or fossil |
| index fossils | is used to identify certain times in history |
| fossils | these are only found in sedimentary rock, the hold any evidence of a once living thing, and they form when organisms die & buried by sediment that hardens perserving the remains |
| trace fossils | indirect evidence such as burrows, footprints or trails left by an organism |
| carbon imprints | this coat of a carbon left in a rock (rock, insects, or soft bodied organisms) |
| molds & casts | form when minerals fill a space left by a dead organism |
| petrified fossils | form when minerals replace the hard parts of an organism |
| preserved remains | occur when an organism becomes trapped in amber (actual body preservation) |
| older & simpler | _________rocks have fossils of _________ organisms. |
| younger & complex | _________rocks have fossils of more ____________ organisms. |
| transitional fossils | the links between organisms are missing |
| evolution | regardless of these "gaps" cast doubt on the overall idea of what? |
| absolute age | uses the decay rate of radioactive isotopes to determine what of fossils or rocks? |
| isotopes & neutrons | ______ are alternate forms of the same element that differ in the number of _________? |
| 6 protons, 8 neutrons | if carbon-14 what are the protons and neutrons? |
| 6 protons, 6 neutrons | if carbon-12 what are the protons and neutrons? |
| parent & daughter | unstable ____________ isotope decay into stable ____________ material at a predictable rate. |
| half life | the time it takes for this to happen to what of the isotope? |
| half. | an isotopes half life is the time it takes for __________ of the parent isotope to break down, or decay, into the daughter isotope/ |
| by measuring the parent-daughter ratio & comparing it to the isotopes half-life. | how is the age of the rock or fossil determined? |
| no, there will always be some amount of the radioactive parent material. that's what makes this type of dating reliable. | will the parent material ever decay completely to a value of 0? |
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