Re: Praclaux Crater and the global flood (fwd)
David Campbell (firstname.lastname@example.org)
Wed, 5 Nov 1997 17:28:02 -0400
Judging from Allen's response, I did not make the context clear enough.
>On Mon, 3 Nov 1997, David Campbell wrote:
>> >If one were to core the lake and pond sediments, one would find a
>> >surprising stratification of a variety of pollen zones.
>> Has this been done? I doubt that stratification is good enough to resolve
>> changes on such a fine temporal scale-bioturbation mixes things very
>Bioturbation may well be a problem today, however, in a multi-event
>Flood catastrophe, bioturbation would be unlikely to occure because of
>the quick succession of burial of each layer. We find multiple layers of
>sediments which reveal no bioturbation, but if today is the sample of the
>past we should find multiple lyares of sediments fully bioturbated.
I was referring to the suggestion that the shifts in pollen
abundance in this crater could reflect seasonal shifts in winds in a
post-flood environment. I do not think these will be distinguishable in
cores due to bioturbation. Also, seasonal shifts should give a more
As Glenn pointed out, bioturbation is a challenge to explain if
large volumes of sediment are attributed to a relatively brief event (e.g.,
most of the geologic column attributed to a single flood). When burrowing
organisms are buried, they try to dig themselves out. Such "escape
structures" occasionally occur in the fossil record, but most burrows show
no sign of encountering trouble. Except in anoxic environments,
bioturbation is worldwide today, with major increases in the past around
the Precambrian-Cambrian boundary and Permian-Triassic boundary.