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0F-Geo History
0F-Geologic History of Earth
Term | Definition |
---|---|
4.6 billion years | the theoretical age of planet Earth |
absolute age | the numeric age of an object or event, often stated in years before the present |
absolute dating | using a dating process, such as radiometric dating, to find the age of an object |
bya | billion years ago |
catastrophe | event causing great and often sudden damage that causes a change or disturbance in Earth's timeline |
chronological order | The arrangement of things in order that they occurred |
emergence | the process of coming into being, or becoming important |
extinction | The permanent disappearance of a species from Earth |
fault | a break in the body of a rock (or rocks) in which one side moves position |
fossil | the trace or remains of an organism that lived long ago |
fossil record | mineralized remains of organisms and the rock layers in which they are found |
fossilization | the process that preserves evidence of life in earth's rock record |
geological time scale | System of chronological measurements that relates stratigraphy (rock layers) to time |
geology | a science that deals with the history of the earth as recorded in rocks |
index fossil | a fossil that is used to establish the age of a rock layer |
marker | event that ends/starts a time division (such as dinosaur extinction) |
multicellular | organism that is made up of several cells working together |
mya | million years ago |
paleontology | the scientific study of fossils |
parent isotope | an element that undergoes nuclear decay |
period | division of geologic history that spans no more than one hundred million years (3rd level) |
petrification | The formation of fossils as stone replaces decaying tissues |
radiometric dating | Technique used to determine how old a rock is by analyzing the amounts of a radioactive isotope and its decay products in the rock (usually Carbon-14) |
relative age | the age of an object in relation to the ages of other objects |
rock strata | Beds or layers of sedimentary rock having approximately the same composition throughout |
sedimentary layers | Layers of rock that are successively deposited on top of one another and are distinguishable from one another based on their mineral content |
single celled | organism that is made up of only one cell |
subsidence | the sudden sinking or gradual downward settling of the ground's surface with little or no horizontal motion |
trace fossil | A fossilized mark formed in sedimentary rock by the movement of an animal |
unconformity | a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time |
uplift | the process by which the earth's surface slowly rises either due to increasing upward force applied from the side or below (tectonic plate movement), or decreasing downward force (weight) from above (glacier melting) |