Term
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Definition
| Tiny particles made of matter |
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Term
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Definition
| all atoms in a particular type of matter are the same |
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Definition
| remains of reefs built by organisms similar to present-day bacteria |
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Definition
| The process by which elements break down by releasing particles and energy. |
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Definition
| The amount of time it takes for half of the radioactive atoms to decay. |
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Term
| What is the difference between Atoms and elements? |
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Definition
| Tiny particles of matter are called Atoms and an when the atoms in a type of matter are the same it is an element |
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Term
| How do scientists use radioactive decay to determine the age of a rock? |
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Definition
| First scientist determine the amount of a radioactive element. Then they compare that amount with the amount of the stable element into which the radioactive element decays |
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Term
| Why is radioactive decay used on igneous rocks? |
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Definition
| Radioactive elements occur naturally in Igneous rock |
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Term
| What is potassium-40 and how is it useful to scientists? |
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Definition
| It is a radioactive element with a half life of 1.3 billion years and it is Useful to date ancient rocks |
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Term
| What is carbon-14 and how is it useful to scientists |
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Definition
| It is radioactive element carbon with a half life of 5730 years and it is useful to determine the age of plants and animals that lived up to about 50,000. years ago. |
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Term
| Carbon 14 dating can only be used to date fossils that are less than how many years old? |
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Definition
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Term
| How do scientists use intrusions to help date sedimentary rock layers? |
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Definition
| They date sedimentary rock above an intrusion to be younger than that intrusion and an intrusion is made of igneous rock and only igneous rock can be used for radioactive dating because sedimentary rocks contain particles from other rocks and radioactive dating would date the particles not the sedimentary rock. |
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Term
| How old are the oldest rocks on Earth? |
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Definition
| About 4.0 billion years old |
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Term
| How old do scientist think earth is and why? |
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Definition
| About 4.6 billions years old because they think that the moon formed when an object from space hit earth and material from both those bodies flew into orbit forming the moon. Radio active dating shows the moon rocks brought back to earth to be about that age. |
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Term
| Why do scientists use a geologic time scale? |
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Definition
| To record the life forms and geologic events in earth's history. |
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Term
| Why do scientists use a geologic time scale: |
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Definition
| They use it to show earth's history.in manageable amounts of time. |
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| What do scientists use to mark divisions between units of geologic time? |
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Definition
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| What are the basic units of geologic time? |
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Definition
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Term
| When did Paleozoic era begin and what types of animals lived during that time? |
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Definition
| 544 million years ago and invertebrates lived |
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Term
| When did the Mesozoic era begin and what animals lived or evolved during that time? |
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Definition
| began 245 million years ago lasted 180 million years and Dinosaurs lived and mammals evolved |
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Term
| The Cenozoic era is often called the Age of.......? |
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Definition
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Term
| Periods are subdivided into what? |
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Definition
| Epochs because it makes events easier to place |
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Term
| How do periods get their names |
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Definition
| Many come from places around the world where geologists first described the rocks and fossils of that period ex. Jurassic refers to Jura Mountains in France |
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Term
| What era of geologic time is subdivided into epochs? |
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| Which era of geologic time has the most complete fossil record? |
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