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Re: K-T mammals

----- Original Message -----
From: "Andrew A. Farke" <andyfarke@hotmail.com>
Sent: Sunday, May 12, 2002 3:59 PM

> New data from 17 Cretaceous-Tertiary (K-T) boundary sections and 53
> vertebrate sites in the Hell Creek and Fort Union Formations in
> North Dakota document a 1.76 m barren interval between the highest
> Cretaceous vertebrate fossils and the palynologically recognized K-T
> boundary.

What kind of rock are these formations, actually? I'm asking because there
has been that suggestion, 5 or 10 years ago, that the barren interval
(assuming this is what the "3-m-gap" has shrunk to) was caused by the acid
rain that dissolved the fossils but not the rock; others said that's
impossible because the rock would have dissolved, too.
        "Palynologically recognized" -- does this mean the famous boundary
layer is not preserved?