From: bivalve (bivalve@mail.davidson.alumlink.com)
Date: Thu Mar 27 2003 - 17:16:02 EST
>> OK I will buy that and thus accept a continuous depostion at 5cm/day.
>You miss the point, Michael. Fine-grained material can be deposited in high-energy environments, which David said was not possible and therefore a problem for YEC.<
But your reference gives no evidence that it was a high energy environment in which the 10-15 cm of diatoms were deposited. On the contrary, it suggests that these were deposited on the beach ("formed on the Oregon coast"), where the flow consistently goes to zero. Like Michael, I had missed your intended point from the quote and thought you were citing it as evidence of high depositional rates.
The laws of physics determine how fast a particle will sink through water. It is possible for fine particles to occur in a particular place on the seafloor in other ways than coming from suspended sediment (generation on the seafloor, e.g. through biological or chemical breakdown of something coarse; movement as a gravity flow along the seafloor; getting clumped and then sinking, e.g. as fecal pellets; etc.). However, different sediment sources will have different sedimentological consequences and thus produce different looking rocks.
Having no experience with the particular beds around the Grand Canyon that you are citing on paraconformities, I do not know what the conventional explanations are in those specific cases. However, all my experience in geology has consistently confirmed that conventional geologic views are a better match for physical reality than young-earth ones, so I am not strongly motivated to look this up. You should be able to find helpful references, e.g on Georef, if you want an answer. I have seen a relatively flat contact between upper Cretaceous and Pliocene strata that had a trace of middle Eocene at the contact. Flat layers had been deposited and eroded, more flat layers were deposited and eroded, etc. with the end result of an unspectacular unconformity representing nearly 70 million years. The color contrast between the Cretaceous and Pliocene deposits makes the change obvious, but the relief of the contact was very low. Homogenous flat layers should erode relatively eve!
nly.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487-0345 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
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