Under great confining pressures, or at depths where temperatures reach a significant fraction of their melting points (typically 10-15 km), rocks that are quite brittle at the surface become sufficiently plastic to deform without fracture at rates comparable to the rate at which fingernails grow (~10 mm/yr).Granted, that makes molasses look downright mercurial, but then relative viscosity is the whole idea here.
The entire Mesozoic Era (295 Ma long) shot by in under an hour, the dinosaurs departed just 20 minutes ago (thank goodness), and we've been comfy and relatively ice-free for only a mere 0.2 seconds.
A healthy human female can expect to live just under 2 milliseconds in a developed country.
Events in the Basin and Range and along the West Coast have also influenced Colorado's physical development, particularly from ~80 Ma on.
Let's pause now to get oriented within and around our region of interest.
The table below collects the links to these headers.
Notice how even deep time can fly in proper perspective: The Precambrian was admittedly a slow start, taking until mid-evening to unfold on our day of creation, but then life as we know it appeared only in the last 3 hours.
After an introductory section, Colorado's geologic history will unfold in chronological order below.
As we come up on major divisions along the geologic timeline, a brief "About Time" header will summarize what event or fossil record breakpoint ushered in the upcoming division and show how it's subdivided.
This geologic overview focuses primarily on the Colorado Rockies and the Colorado Plateau, but adjoining portions of Wyoming, Utah and the High Plains as far east as the Black Hills of South Dakota also have important and related stories to tell.