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.
How much energy is required to erode and move enough sediment to deposit
thousands of feet across the whole southwestern U.S. and how do the tiny
little reptiles survive this process? 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.
S> How does one deposit thousands of feet of sedimentary rock in a violent
S> flood and then form a sandstone bed with dinosaur tracks on it?
K> When the tide goes out, wouldn't one expect the remaining dinosaurs to make
K> tracks where they could?
S> Tides? We're talking about a flood which may have already deposited several
S> thousand feet of sediment! I would imagine there would be nothing left to make
S> footprints after such an event!
K> After the event? We're talking about during the event, before even all the
K> land area is fully eroded. When it was fully eroded there would be no
K> place to make subaerial footprints, until the ocean floors sank and land
K> areas emerged. But during the rise of the waters, dinosaurs would be sure
K> to walk uphill whenever they could, including between tides. Wouldn't you
K> expect tides in a worldwide water catastrophe?
You're being disingenuous here. Dinosaur tracks are not found down near the
base of the Cambrian (the earliest "flood" sediments). They are found only in
Mesozoic-age rocks. Mesozoic rocks in the western U.S. typically have thousands
of feet of Paleozoic age rocks beneath them. Those Paleozoic rocks are presumably
flood sediments. Those dinosaurs had to leave tracks after MOST of the flood
sediments HAD ALREADY BEEN DEPOSITED. Presumably after the highest mountains
had been covered by flood waters leaving the poor dinosaurs no place to walk to
in their escape.
If I'm misrepresenting your position, perhaps you could explain exactly what
you are envisioning regarding which sediments are flood sediments and which
sediments are not flood sediments and how long the flood lasted.
S> Or develop a paleosol?
K> Are you convinced that the silty layers called paleosols were actually
K> formed slowly, then preserved in situ (usually with no unconformity)? I
K> am not. Even those with root casts in them are not necessarily slowly
K> formed. If they were the roots would have decayed. Even vertical
K> petrified trees in growth position are, on closer inspection, by many
K> evidences, found not to be in growth location.
S> Your strategy here is to mention a couple of examples where there may be
S> debate as to whether or not a particular paleosol is indeed a preserved soil
S> horizon. I would counter with "Are you convinced that ALL of the thousands
S> of localities where paleosols have been recognized are not paleosols, indeed,
S> that paleosols don't even exist?"
K> Although I have not looked at ALL of them, my simple answer is, until the
K> Neogene, yes. And many in the Neogene may not be true soils either.
K> Appologies to those who are convinced that they are, but I find it hard to
K> be so convinced.
K> Just one example -- on my table here some leaf fossils from Yellowstone
K> Fossil Forest, with as good preservation at the base of the "soil layer" as
K> on the top. No decay. Most of these fossiliferous silt layers are fairly
K> homogeneous, and less than 10 cm thick (many less than 1 cm thick), and
K> latterally they pinch out, or form lenses.... about what you would expect
K> in a silt layer at the bottom of a lake, before the next load of volcanic
K> breccia came in. Not soils, but silt layers. Give me you best documented
K> example of a real fossil soil.
I'm a structural geologist, not someone normally concerned with paleosols, but
I would recommend a collection of papers by those who are experts:
Reinhardt, J. & Sigleo, W. R. (editors) 1988. Paleosols and Weathering Through
Geologic Time: Principles and Applications. Geological Society of America
Special Papers 216.
They list numerous examples of paleosols from different geologic periods from
areas around the country.
S> What about a limestone on top of thousands of feet of flood deposits
S> containing an in situ coral reef with associated fragile crinoids or
S> bryozoans preserved as well?
K> In many such reef structures the fossils are not really organically bound,
K> but are suspended in the matrix. Capitan Reef, for example, has been
K> recognized as a gigantic debris flow. Some reefs that show organic
K> structure are oriented upside down. They were probably transported from
K> where they grew -- which would suggest high-energy water movement. The
K> reef problem is very interesting.
S> Capitan reef has NOT been recognized as a giant debris flow (except maybe
S> by young-earth creationists who, once again, cannot have even one in situ reef
S> in the geologic record or their model collapses). I refer interested people
S> to a neat web site at:
S>
S> http://www.science.ubc.ca/~eoswr/slidesets/guad/slidefiles/guadc0.html
K> Actually, I was indirectly quoting a person on a GSA fieldtrip to Capitan
K> Reef who looked at the evidences for turbiditic structure (classical Bouma
K> sequences) in the Yates formation (in the "backreef"), if I remember
K> correctly, one who believed in long ages but recognized evidence of rapid
K> emplacement of this whole set of formations. That may not be the accepted
K> view in the present literature, but on that fieldtrip many of the men recognized
K> it as such.
It's not uncommon to find breccias and debris flows in the forereef or backreef
areas around large reefs like Capitan (as a matter of fact, they're expected). That
has no bearing whatsoever on the question of whether or not the reef itself is in situ.
S> I would also remind people that reefs are EXTREMELY common in Paleozoic
S> carbonates around the world.
K> That's where the upside-down (obviously transported) one I mentioned is.
K> Bioherms like that one were clearly transported as a unit. Other "reefs",
K> without real organically bound fossils (apparently not in situ coral reefs,
K> but still called "reef structures" because of their shape) were transported
K> broken up in limey mud from the area(s) where the organisms had grown.
Just because SOME bioherms found in sedimentary rocks were transported doesn't
mean that ALL were therefore transported. You've searched for examples of transported
reefs and found a couple, big deal. You're ignoring the bulk of them which clearly
formed in situ (e.g. Silurian pinnacle reefs around the Michigan Basin to name one
group of them).
S> Funny thing how, if they're all transported, that only tabulate corals ended
S> up in Devonian/Silurian age rocks while Cenozoic rocks just have scleractinian corals
K> Yes! While many other classes of Coelenterates (Porifera, Hydrozoa, and
K> even Alcyonarids (Octocorallia, the "soft corals") continue through the
K> permo- triassic transition fairly smoothly, the Tabulata and Tetracorallia
K> die out entirely, and Scleractinians (and other Hexacorallia) begin. To
K> me, this points to a possible sensitivity of the Tabulata and
K> Tetracorallia, which caused their extinction when conditions changed.
K> Perhaps the waters where they lived (with trilobites, brachiopods, and the
K> rest pf the Paleozoic marine organisms) were not as saline as our seas are
K> today, and these corals, in contrast to many of the other forms, could not
K> survive inundation with water of greater salinity (or some other
K> condition). Whatever it was, they did not survive. The lack of
K> scleractinian remains with them indicates to me that the scleractinians did
K> not live in the same place. They are found with Mesozoic (and Cenozoic)
K> fossils, so I believe they lived in the waters of areas inhabited by
K> "Mesozoic" animals, and they survived to speciate in the postflood seas.
Once again, other than your ad hoc pleading, you are presenting no evidence
that Cenozoic, Mesozoic, and Paleozoic organisms inhabited different environments.
S> (makes a lot of sense from an old-earth, evolutionary point of view,
K> Do you think the Scleractinians evolved from Tabulates? Or a common ancestor?
I think it's an observable fact that Tabulates lived and thrived many millions
of years earlier than Scleractinians and that different groups of organisms (not
just cnidaria) were the dominant reef-builders at different periods of time.
I don't know enough about the evolution of cnidaria to discuss their phylogenetic
relationship.
S> none whatsoever from a young-earth or flood-model view).
K> Depends on your viewpoint. Making sense out of the fossil record from a
K> flood perspective is a challenge and a joy to me. There is always more to
K> be learned.
There's more to be learned, I'll grant you that!
We all have to examine our motives. If we're doing research hell-bent to
prove or disprove some particular idea that we're emotionally attached to,
then I think we should step back a bit and examine whether or not we're really
looking at the evidence fairly.
- Steve.
-- Steven H. Schimmrich, Assistant Professor of Geology Department of Geology, Geography, and Environmental Studies Calvin College, 3201 Burton Street SE, Grand Rapids, Michigan 49546 sschimmr@calvin.edu (office), schimmri@earthlink.net (home) 616-957-7053 (voice mail), 616-957-6501 (fax) http://home.earthlink.net/~schimmrich/