Re: Flood Model and ichnofossils
Karen G. Jensen (kjensen@calweb.com)
Wed, 10 Feb 1999 13:14:50 -0600>This discussion is getting complicated! Karen Jensen's statements are "K"
>and
>my previous statements are "S":
>
>K> Again, let's look a little deeper.
>K> You wrote, and responded to my reply:
>
>S> 3. The occurrence of ichnofossils (trace fossils like burrows, tracks,
>S> coprolites, root casts, etc.) seems difficult to understand in the
>S> context of a global flood with rapid sedimentation.
>
>K> They seem difficult to understand in the context of slow sedimentation,
>K> too. If seafloor sedimentation were gradual, tracks and burrows would be
>K> quickly destroyed by continuing bioturbation. The presence of tracks, etc.
>K> indicates quick preservation before disintegration.
>
>S> So we have quick preservation, big deal. It rains, animals walk in
>the mud
>S> on a river bank and leave tracks, the river rises (it's raining) and
>sediments
>S> cover the tracks. It doesn't indicate a global flood and, most
>importantly,
>S> you're ignoring the fact that trace fossils occur THROUGHOUT the
>sedimentary
>S> record. How do animals stroll about in the middle of a flood after
>THOUSANDS
>S> of feet of sediment have ALREADY been deposited?
>
>K> I don't mean to ignore that. Some of the trace fossils are in the
>K> Cambrian, like trilobite tracks, suddenly covered by turbidites, or worm
>K> burrows that go up and up and up through successive layers of silt (and I
>K> suspect may be the same individuals hurridly trying to climb up out of
>K> rapidly deposited layers, until they got out or gave out). The many tracks
>K> and burrows higher in the column are also fascinating -- like the famous
>K> amphibian tracks in the Coconino sandstone. Why would you think there
>K> would be no amphibians left alive after the first few minutes or days
>of the
>K> onset of a flood? Animals that float don't mind how many thousands of
>feet of
>K> sediments are being deposited below them.
>
> Let's think about those numerous amphibians AND reptiles who left tracks in
>the Coconino Sandstone. Imagine we're a little reptile and we live in
>northern
>Arizona in the days of Noah. We crawl around on the Precambrian Vishnu Schist
>looking for bugs to eat. We didn't get the call from Noah to travel to Israel
>and get onto the ark so when it starts raining we get a little worried. We
>climb to higher ground and then the waters overtake us. We're a good swimmer
>so we can stay afloat for a time paddling about.
>
> Now, here's the good part, some 3,000 feet of sediment comes from somewhere
>(where?) and is deposited beneath the poor little swimming reptile. At some
>point, the water drops enough or the sediment rises enough for the reptile to
>leave footprints on the surface of the sediment. As a matter of fact, a bunch
>of reptiles and amphibians started leaving footprints. Keep in mind that not
>one mammal left a footprint on the Coconino (Permian age). Then the waters
>rise again and they all die.
Amphibian body fossils are indeed preserved in sediments other than the
trackway layers. One interesting observation is that the trackway layers
are in lower parts of the Coconino in the northeastern part of the Grand
Canyon area and in the upper parts in exposures to the southwest. The
paleocurrent direction is from NE to SW. Almost paints a picture, if you
want to, as you have above!
>
> How much energy is required to erode and move enough sediment to deposit
>thousands of feet across the whole southwestern U.S.
A whole lot! When you look at the megabreccias at the base of the Tapeats
sandstone, it boggles our little minds. And that was just the beginning of
the thousands of feet.
and how do the tiny
>little reptiles survive this process?
A lot of them probably died. But enough of them survived that during the
Coconino depostion they were able to leave millions of trackways.
I'm assuming that the erosion and transport
>that much sediment requires energy in the form of quickly moving water. It
>truly boggles the mind.
>
Yes, it does. No kidding.
2Peter 3:6-7
Your sister in Christ,
Karen