Mineral assemblages dating techniques

The wavy fabric indicates solid flow at mid-crustal temperatures of 400-500C.

To recast barely conceivable geologic time intervals in a more familiar format, they'll also appear from time to time as military hours in a single 24-hour day (and all-nighter) of creation beginning at the planet's formation and ending with the here and now.

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 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.

And so it goes with the bending of seemingly rigid rocks, the cutting of majestic canyons, the raising and erasing of entire mountain ranges, the opening and closing of globe-girdling oceans, and the incessant splitting and regrouping of the dancing continents.

Our usually reliable day-to-day sensibilities tell us that such things can't happen, but they can and do happen because solid rock reveals its malleability only over time scales very long compared to human eventstypically in spans of tens of thousands if not millions of years.

But the effort pays, for with a feel for deep time comes a sense of its great power: Given enough time, almost anything energetically possible can happeneven at very large scales.Given enough time, cold surface rock will yield to flowing water and buried rock will bend or even flow rather than break.The planet's had ample time for all of this, even if it's out of our ken.I've attempted to point out the most significant unknowns and disagreements, but often, rightly or wrongly, I've simply taken sides.If you take nothing else away from this humble attempt, please consider this: Of Colorado's 55 Fourteeners, all but 2 (Longs Peak and Pikes Peak) lie either along the Colorado Mineral Belt or on the shoulders of the Rio Grande Rift.

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