front 1 evidence that an organism once existed in an area; can be a part of the organism's body or a trace fossil which is a mark or print left by the organism | back 1 fossils |
front 2 the record of geologic time, divided into eons, eras, periods, epochs, and ages | back 2 geologic time scale |
front 3 the information about Earth's history that can be gathered from fossils | back 3 fossil record |
front 4 the permanent loss of a population or species | back 4 extinction |
front 5 fossils of organisms belonging to species that existed in large numbers for a relatively short amount of geologic time; used to date the rocks in which they are found | back 5 index fossil |
front 6 extinct marine arthropods that form one of the earliest known groups of arthropods, the first appearance of these in the fossil record flourished throughout the lower Paleozoic time period | back 6 trilobite |
front 7 the scientific law stating that, in undisturbed rock layers, each layer is younger than the layer beneath it, and older than the layer above it | back 7 law of superposition |
front 8 the dating of events based solely upon the order in which they occurred | back 8 relative age |
front 9 the process of comparing objects or events to determine which are younger or older, without knowing their specific ages | back 9 relative dating |
front 10 the age given in years, of a fossil, a rock, a feature, or an event; usually determined through radiometric dating | back 10 absolute age |
front 11 the process of measuring the specific age of an object or event in terms of years, a time range, or actual date | back 11 absolute dating |
front 12 measurement of the amount of radioactive material (usually carbon 14) that an object contains; can be used to estimate the age of the object | back 12 radioactive dating (radiometric) |
front 13 a type of rock formed by gravity pressing fragments of other rocks and minerals together as they settle on land or under the ocean over a long period of time | back 13 sedimentary rocks |
front 14 a type of rock that forms when melted rock cools and hardens | back 14 igneous rock |
front 15 a sample of ice taken by a hollow tube from a glacier or other large ice body | back 15 ice core |
front 16 the average weather conditions in an area | back 16 climate |
front 17 a crack in a body of rock that the rock can move along | back 17 fault |
front 18 an imagined horizontal line across the plane | back 18 strike |
front 19 The relative displacement of originally neighboring points on opposing walls of a fault | back 19 slip |
front 20 the angle of inclination measured downward from horizontal. | back 20 dip |
front 21 a large natural structure on the earth's surface such as a mountain, a plain, or a valley | back 21 landform |
front 22 a break in time in an otherwise continuous rock record | back 22 unconformity |