| Term | Definition |
|---|
| Law | Fact that does not explain why |
| Theory | An accepted hypothesis that explains why |
| Hypothesis | An educated guess based on opinion, observation, and judgment |
| Example of a Law | What goes up, must come down |
| Example of a Theory | The surface of the Earth has changed very slowly because of erosion and deposition |
| Example of Hypothesis | If you eat one pound of carrots each day for a week then your skin will start turning orange |
| Fossils are | any naturally preserved evidence of life, most often preserved in sedimentary rock, usually formed from hard parts of an animal such as bones and shells |
| trace fossil | naturally preserved evidence of an animals activity. |
| coprolite fossil | fossilized dung |
| index fossils | used to help find out the relative date of layers of rocks. These are fossils of animals that lived for only a short, well-defined time period |
| lithification | The process becoming a rock |
| Relative Dating | Determining if an object or event is older or younger than another object or event |
| Superposition | is the law that says younger rocks are above older rocks in an undisturbed sequence |
| James Hutton | known as the Father of Modern Geology, is known for creating the theory of Uniformitarianism. This says Earth’s surface and features change “slow and steady” through erosion and deposition |
| The Geologic Column | is an ideal sequence of all rock layers in order from youngest to oldest. |
| Isotopes | have extra neutrons, which makes them radioactive. There are two kinds of isotopes. |
| Parent isotopes | unstable = radioactive and will decay |
| Daughter material | stable = not radioactive and will NOT decay |
| Radioactive decay | when unstable parent isotopes turn into stable daughter isotopes. |
| half-life | the time it takes for one half of the parent isotopes to decay (change) into daughter isotopes. |
| To find the absolute (exact) age of a rock | you need to know the rate of decay of a radioactive element in a rock. |
| Different kinds of isotopes | have different rates of radioactive decay |
| Carbon-14 | is a type of radiometric dating used to find the absolute age of once living materials under 50,000 years old |
| Isochron | dating is a type of radiometric dating used to find the absolute age of rocks that are over 100 million years old |
| Mass Spectrometer | is a sophisticated piece of scientific equipment used to measure the amounts of parent and daughter isotopes in rocks when using absolute dating |
| To use a Mass Spectrometer | a rock sample must be crushed and separated into separate minerals. These minerals must then be dissolved in an acid, turning them to salts. These salts are then ran through a Mass Spectrometer that counts parent and daughter isotopes. |
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