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Period: 541 BCE to 250 BCE
The Paleozoic era
The Paleozoic era occurred from the time frame of 541 million years ago to 251 million years ago. At this time Colorado was covered with a shallow sea. Some sediments were deposited and accumulated on top of the ground. Around 300 million years ago the ancestral Rocky Mountains formed by an uplifting due to a collision and were though to be as high as ten thousand feet. Erosion occurred and the mountains disappeared. -
Period: 251 BCE to 66 BCE
The Mesozoic Era
The Mesozoic Era occurred in the time frame of 251 million years ago to 66 million years ago. Over time shale, sand, and volcanic ash formed and the sea flooded this area. When the sea decreased the existing formation had another layer which consisted of fossils and limestone. During this time the Laramide orogeny occurred and it was caused by subduction, folding and mountain building. This was a shallow subduction which caused an uplifting of the Rocky Mountains in Colorado. -
Period: 66 BCE to
The Cenozoic Era
The Cenozoic Era has happened for 66 million years up until the present day. The Laramide orogeny up until twenty million years ago. During this time frame, there were volcanic eruptions in Colorado. Colorado was also affected by an ice age that occurred around one million to ten thousand years ago.