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Field Division of Education The Geology of Rocky Mountain National Park |
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GEOLOGICAL TIME SCALE
| PSYCHOZOIC or RECENT ERA | Mental Dominance | |
| CENOZOIC ERA 3% of Geol. Time. 60,000,000 years. |
Pleistocene or Glacial Epoch- | Periodic glaciation and appearance of man. |
| Pliocene- | Cooling of climates. | |
| Miocene- | Culmination of mammals and land floras. | |
| Oligocene- | Rise of anthropoids. | |
| Eocene- | Spread of modernized mammals. | |
| Paleocene- | Expansion of archaic mammals. | |
| MESOZOIC ERA 7% 140,000,000 years. |
Cretaceous- | Last of ammonites and dinosaurs. |
| Jurassic- | Rise of toothed birds, great expansion of reptiles. | |
| Triassic- | Rise of dinosaurs, pterodactyls etc. | |
| PALEOZOIC ERA 17% 340,000,000 years. |
Permian- | Periodic glaciation in s. hemisphere, extinction of trilobites, spread of primitive insects. |
| Pennsylvanian- | Warm, humid, climate with extensive coal making. Dominance of spore floras. Spread of reptiles. | |
| Mississippian- | Spread of ancient sharks and culmination of crinoids. | |
| Devonian- | Rise of amphibians, marine fishes, and primitive amnonites. First spread of forests. | |
| Silurian- | Rise of air-breathing invertebrates. Spread of Paleozoic reef-corals. First known occurrence of land plants. | |
| Ordovician- | Rise of fresh-water fishes and corals. Spread of molluscs. Culmination of trilobites. | |
| Cambrian- | Rise of shell-bearing molluscs. Dominance of trilobites. First appearance of well-known marine faunas. | |
| PROTEROZOIC ERA | Primitive Marine Life. An early and late glacial period. | |
| ARCHEOZOIC ERA | The oldest known life. Geologic history very obscure. Archeozoic and Proterozoic include approximately 75% of geologic time, or have a duration of 1,500,000,000 years. | |
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Last Modified: Sat, Feb 9 2002 10:00:00 am PDT |
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