Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Geologic Time Unit
unit 3 vocabulary
| Term | Definition |
|---|---|
| fossil | the preserved remains or traces of living things |
| sedimentary rock | the type of rock made from hardened sediments, where fossils are most commonly found |
| mold | a hollow area in sediment in the shape of all or part of an organism |
| cast | a solid copy in the shape of an organism, forms when minerals are deposited in a mold |
| petrified fossil | fossils in which minerals replace all or part of an organism |
| carbon film | an extremely thin coating of carbon on rock |
| trace fossil | provides evidence of the activities of ancient organisms (footprints, trails, burrows) |
| paleontologist | scientist who studies fossils |
| scientific theory | a well tested concept that explains a wide range of observations |
| evolution | the gradual change in living things over long periods of time |
| extinct | something that no longer exists and never will live on Earth again. |
| relative age | the age of a rock compared to the ages of other rocks (tells older or younger) |
| absolute age | the number of years since the rock formed |
| law of superposition | used to determine the relative ages of sedimentary rocks; in horizontal rock layers, the oldest layer is at the bottom and each layer higher is younger than the one below it |
| extrusion | lava that hardens to form rock on the surface of the earth (are younger than the rock layers beneath it) |
| intrusion | magma that hardens to form rock beneath Earth's surface (are younger than the rocks around it) |
| fault | a break in earth's crust (younger than the rock it cuts through) |
| unconformity | a gap in the geologic record made by a younger layer of rock meeting a much older layer beneath it |
| index fossil | certain fossils that are widely distributed and represent a type of organism that lived only briefly which helps geologists match and date rock layers. |
| atom | tiny particles of matter |
| element | matter in which all the atoms are the same |
| radioactive decay | certain atoms break down to form atoms of another element releasing particles and energy |
| half-life | the amount of time it takes half of and element's radioactive atoms to decay |
| geologic time scale | the record of life forms and geologic events in Earth's history |
| era | larger divisions of geologic time |
| period | subdivisions of eras |
| Cenozoic Era | The era we presently live in - referred to as the "age of mammals" |
| Mesozoic Era | the "age of reptiles" - dinosaurs were a major life form during this era |
| Paleozoic Era | The earliest era of geologic time |
Created by:
sdix
Popular Earth Science sets