quote:
Originally posted by Tranquility Base:
Remember the entire Precambiran systematically has near zero paleocurrents. I really think that is what you will see for the normal situation. If you think currents sufficient to generate continent wide paleocurrents are the norm then why zero currents in the Precambrian marine beds?
Precambrian sedimentary deposits are poorly represented, hence few paleocurrents from the Precambrian. But it looks to me like they are relatively well represented. Perhaps you can better explain your position, I'm (obviously) a bit confused.
http://geology.swau.edu/paleocur/precatot.html
As for the Hoodoos, they are caused by a water resistant rock (such as basalt) covering less resistant or more porous rock (limestone or sandstone). Rainwater will have access to the entire structure except rock directly under the basalt (or whatever) cap. The result is the rest of the formation eroding away except the basalt boulder and the sandstone underneath, now holding it high in the air.
You can see something rather similar happen in miniature when pebbles rest upon clay or silt that is exposed to rain, since most of the erosion is from the impact of raindrops, the rest of the clay bed washes away, leaving the pebbles elevated a few centimeters above the ground, now supported by pillars of clay directly underneath.
Ah the joy of a childhood spent walking into stuff.
quote:
TrueCreation Are we aware of any "paleohoodoo's"?
I'm not the one to ask. *But* I think there *could* be such a thing. The place to look would be 'fossil' dunes or perhaps other aeolian deposits. It sounds like a terribly esoteric thing to look for but might give clues regarding paleoseismology.
[This message has been edited by gene90, 06-13-2002]