Thu, 20 Nov 1997 06:12:43 -0600 you wrote:
>But there are animal burrows in nearly every geologic layer. That is
>evidence of slow deposition in every layer.
If deposition were slow, wouldn't there be time for animals to burrow a
lot, and completely bioturbate the sediment (which they can do in a few
hours)? In that case the laminae would be disturbed, and many burrows
would be obscured also.
But if deposition were rapid, they would only burrow as long as they were
able, usually falling far short of completely bioturbating the sediment.
Most layers have undisturbed laminae and the animal burrows (if any) are
often distinct. Isn't that what would be expected during rapid
sedimentation?
Karen