Re: Four Rivers Revisited

Allen Roy (
Mon, 3 May 1999 12:07:41 -0700

> > Jonathan wrote:
> > In a catastrophic setting, the sandstones would be deposited from
> > or silicate rich waters. The deposit would become cemented by
> > minerals from the water solution which saturates the sands. One need
> > wait for reletively slow percolation to do the job.
> Fast or slow, the cement must be deposited from fluids percolating
through the
> sediment (unless you believe it materialises from the 4th dimension).

I was trying to make the point that if the sediment was lain by water
deposition, then one would not need fluids to percolate through the
sediment because the sediments would already be highly saturated with
fluids containing the cementing minerals in solution. The fluids would
eventually leave the sediment (percolate out?) leaving it cemented

> You did not mention Roman cement in the first instance, but specifically
> Portland cement. Roman cement was indeed made from lime. On addition
> water lime forms calcium hydroxide, or slaked lime. Like the hydrated
> calcium-aluminosilicates of Portland cement this has no counterpart in
> geological world (at least that I am aware of).
> I have no problem with rapid cementation by carbonates. Cementation
rates are
> very variable, some deep sea oozes are uncemented even at great depth,
> sediments cement instantaneously. There are ways of determining which is
> relevant to a particular example. The types of sediments and the
environments in
> which you get rapid cementation are well known, as are those unlikely to
> it. If we are to discuss cementation, let us use realistic examples.
Please do
> not bring in red herrings about concrete or roman cement, they are not
> relevant.

Alright, my use of Portland cement was not the best example. I was trying
to point out that rapid hardening could account for some of the Flood
depositions being broken up and moved about while during the same
catastrophe. The minerals in solution during various stages of the flood,
likely in concord with the source region of impact tsunami, could provide
ready cementing minerals in abundance (or lack thereof) contained within
the fluids in the sediments as they are lain. That would be the
depositional environment of the sediments.