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Science test#5

Relative Age Age of a rock compaired to other rock layers.
Fossile Zny trace, or imprint or remains of a liveing thing preserved in Earth's crust.
Half- life The time it takes for half of the mass of a radioactive element to decay into another element
Absolute Age Age of a rock by compairing the original element amount of decay products present
Era Long streaches of time to mesure Earht's geogolical history
Peroid One of the primary divisions of a geogolical era.
Original Horizontiality Sedimentary rock forms in horizontial layers.
Superposition In a serious of rock layers, the bottom layer is the oldest and the top is the youngest.
Geologic comomn Listings of earth's rock layers from oldest to youngest
Cast Organisms covered by sediment soonn after death, soft parts decay and hard parts (bones, teeth) last long enough to be preserved.
Imprint Buried or squeezed between layers and fluids removed.
Petrifited Buried organisms trapped in sediment.
Index fossile Live for a short peroid of time widespread over earth and evove rapidly.
Trilobites Sea animals.
Precambrian Began 4.6 billion years ago earths formation earliest life formed in sea multi- cellur, marine organisms few fossils
Paleozic 600 Million years ago life abundunt sea and land insects amphibans trilobites fish reptiles farests.
Mesozic 245 Million years ago dinosaurs mammles birds flowering plants pangea began to break apart climats milder
Cenozoic 65 Million years ago mammles dominate humans appear about 2 million years ago.
Peroid Part of era associated with major changes in earth's crust.
Geogoligical timescale major events and life forms on earth during each era.
Created by: 18nnezz