[dr_lew]

Not sure how they figure 200 million years. More apropos is how long it had left assuming natural erosion. I’d guess not more than 1000 years, and maybe more likely 100. Not to condone this sort of thing, you understand, but geez.

[frankenMonkey]

From this:


To this:

Takes millions and millions of years.
And the damage those jack asses have done will remain for a thousand or more.

[stormer]

Entrada sandstone - 140 -180 million years. Here’s the USGS page discussing it: http://3dparks.wr.usgs.gov/coloradoplateau/lexicon/entrada.htm

When you get done reading the literature sited get back to me.