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Science Ch.2
Geologic Time
| Question | Answer |
|---|---|
| Geologic Time Scale - | A record of the Earth's geologic history |
| Strata - | Layers of different rock types |
| Eon - | The largest division of the geologic time scale, spans hundreds to thousands of millions of years |
| Eras - | Divisions that span time periods of tens to hundreds of millions of years |
| Period - | A division of geologic history that spans no more than one hundred million years |
| Epoch - | The smallest division of the geologic time scale |
| James needs to write a report which will describe the ups and downs of mammals in a previous time period. Which should he use, eons or epochs? Why? | Epochs, because epochs are the smallest division of the geologic time scale and are used to describe the evolutionary ups and downs of mammals and birds |
| Why do many geologists study layers of strata? | They want to learn more about the history of the Earth |
| The Triassic, the Jurassic, and the Cretaceous _____ make up the Mesozoic era | Periods |
| James needs to write a report which will describe the ups and downs of mammals in a previous time period. Which should he use, eons or epochs? Why? | Epochs, because epochs are the smallest division of the geologic time scale and are used to describe the evolutionary ups and downs of mammals and birds |
| The Mesozoic Era was the Age of Dinosaurs, and the current Cenozoic Era is the Age of _____. | Mammels |
| Why do many geologists study layers of strata? | They want to learn more about the history of the Earth |
| How does an eon differ from an era? | An eon spans hundreds to thousands of millions of years, while eras span tens to hundreds of millions of years |
| Georges Cuvier - | Helped establish our current understanding of the history of Earth. He studied sedimentary rocks, began comparitive anatomy, named the pterodactyl |
| The Triassic, the Jurassic, and the Cretaceous _____ make up the Mesozoic era | Periods |
| James Hutton - | Thought that most of the features on the surface of the Earth were formed by slow, ongoing, geologic processes |
| Uniformitarianism (Gradualism) - | The theory that Earth's features are mostly accounted for by gradual, small-scale processes that occurred over long periods of time |
| The Mesozoic Era was the Age of Dinosaurs, and the current Cenozoic Era is the Age of _____. | Mammels |
| How does an eon differ from an era? | An eon spans hundreds to thousands of millions of years, while eras span tens to hundreds of millions of years |
| Georges Cuvier - | Helped establish our current understanding of the history of Earth. He studied sedimentary rocks, began comparitive anatomy, named the pterodactyl |
| Catastrophism - | The theory that Earth's features are mostly accounted for by violent, large-scale events that occurred in a relatively short amount of time |
| James Hutton - | Thought that most of the features on the surface of the Earth were formed by slow, ongoing, geologic processes |
| Uniformitarianism (Gradualism) - | The theory that Earth's features are mostly accounted for by gradual, small-scale processes that occurred over long periods of time |
| Today, geologists believe mostly in _____, with a little bit of _____. | uniformitarianism; catastrophism |
| James Hutton's theory of _____ earned him the title of 'The Father of Modern Geology.' | uniformitarianism |
| Catastrophism assumes that the Earth's landscape was shaped by _____. | violent, short-lived natural events |
| The change from catastrophism to uniformitarianism made scientists decide that Earth must be _____ than previously thought. | older |
| How did the Bible influence Cuvier's view that the Earth is relatively young? | The catastrophes in the Bible seemed to be on such large scales that they could account for the creation of things like mountains |
| Relative Dating - | Scientists compare different layers of rock to determine an ordered sequence of events in geologic history |
| Stratigraphic Succession - | The way rock layers are built up and changed by geologic processes |
| Fossil Succession - | A method in which scientists compare fossils in different rock strata to determine the relative ages of each |
| Radioactive Decay - | Emission of energetic particles to produce new elements |
| Radiometric Dating - | The method of using radioactive decay to determine the age of rocks |
| Rock Strata A contains Fossil X. It is below Rock Strata C which contains Fossil Z. Rock Strata B contains Fossil Y. It is above Rock Strata C. Which of the following is the correct order of the fossils (from oldest to youngest)? | X, Z, Y |
| In stratigraphic succession, scientists study the various _____ of rock. | Layers |
| Scientists couldn't perform numerical dating of rocks until they discovered _____. | Radioactive decay |
| The statement Rock A is fifty years older than Rock B is an example of _____. | Relative dating |
| The statement Rock A is seventeen years old is an example of _____. | Numerical dating |
| Principle of Original Horizontality - | States that all rock layer were originally horizontal |
| Law of Superposition - | The youngest rock layers are closest to the top |
| Principle of Cross-Cutting Formations - | Rock formation that cut across other rocks must be younger than the rocks they cut across |
| Inclusions - | Foreign bodies of rock or mineral enclosed within another rock. Inclusions are always older than the sedimentary rock within which they're found |
| Unconformities - | Interfaces between discontinuous layer of rock |
| Any fault lines or igneous intrusions that cut across a set of rock strata must be _____ that set of rock. | Younger than |
| An interface between discontinuous layers of rock is called _____. | An unconformity |
| The Principle of Original Horizontality applies only to _____ rocks. | Sedimentary |
| If Sedimentary Layer A occurs above Sedimentary Layer C and Sedimentary Layer B is below Sedimentary Layer C, which of the following is the correct order of the layers (from oldest to youngest)? | B, C, A |
| Any inclusion found within sedimentary rock must be _____ that rock. | Older than |
| Radiometric dating (also known as radioactive dating) - | A method used to date rocks based on the known decay rate of radioactive isotopes |
| Radioactive decay - | The process by which an unstable atomic nucleus loses energy by releasing radiation |
| Parent nuclide - | The unstable nuclide that undergoes radioactive decay |
| Daughter nuclide - | The nuclide that results from radioactive decay |
| Alpha decay - | A type of radioactive decay where an alpha particle is emitted |
| Beta decay | A type of radioactive decay where a beta particle is emitted |
| Alpha particle - | 2 protons and 2 neutrons bound together |
| Beta particle - | An electron that is emitted from the nucleus |
| Gamma decay - | A type of radioactive decay where a gamma ray is emitted |
| Gamma ray - | A high energy photon |
| Radiometric dating is a method used to date rocks based on what? | The known decay rate of radioactive isotopes within the rocks |
| Which of the following types of radioactive decay does not result in a change in the number of protons and neutrons within a nucleus, but does release a lot of energy? | Gamma Decay |
| A large nucleus may get to a more stable state by emitting two protons and two neutrons. This describes which type of radioactive decay? | Alpha Decay |
| Which of the following is the term used for the process by which an unstable atomic nucleus loses energy by releasing radiation? | Radioactive decay |
| Half-life - | The time required for a quantity to fall to half of it's starting value |
| A scientist would not be able to use radiocarbon dating to find the age of which of the following samples? | Stone from a 1,000-year-old settlement |
| Which of the following terms is used to describe the process by which an unstable atomic nucleus loses energy by releasing radiation? | Radioactive decay |
| Which of the following terms is used to describe the time required for a quantity to fall to half of its starting value? | Half-life |
| In uranium-lead dating, we see that two unstable uranium isotopes decay into stable lead isotopes. Which of the following statements is true about this decay? | Uranium-238 decays to lead-206; uranium-235 decays to lead-207 |
| Which of the following statements is true of radiocarbon dating? | The half-life of carbon-14 is 5,730 years, and carbon-14 decays into nitrogen-14 |