This is the latest that I am aware of on the fossilization front.
At 10:22 PM 1/7/98 -0600, bpayne@voyageronline.net wrote:
>Tue, 06 Jan 1998 23:02:15 -0600 Glenn Morton wrote:
>
>> Alkaline waters, I am told, can preserve things quite effectively. The fact
>> that there are huge flamingo nests there combined with the fact that in
>> Africa Flamingos live in the alkaline lakes of the rift valley, makes a
>> convincing explanation.
>
>OK for flamingo nests which rest on the bottom anyway, but you didn't
>refer to fish which _float_ when dead. Do the bottoms of the alkaline
>lakes of the rift valley contain varved sediments with fossil (or
>proto-fossil) fish buried in the sediments?
>
>You have not answered this YEC argument for catastrophic deposition.
It is amazing to me how God often provides information immediately before I
need it. Today I at work, the circulating copy of Geology (Dec. 1997)
landed on my desk and I read it at lunch. The article reminded me of how
animal fosillization occurred, even though that article was involved in how
leaves fossilize. The article says,
"Terrestrial leaf fossils often form through authigenic preservation in which
the leaf surface is coated by a variety of minerals, especially iron oxides.
The mechanism of this fossilization is unclear, because the largely
hydrophobic leaf surfaces do not readily bind metal ions. Previously proposed
mechanisms for mineral encrustation include precipitation of minerals in
sediment pore spae and precipitation of iron oxides at the surface by
decay-produced CO2. Here we demonstrate that diverse bacterial species rapidly
colonize leaf surfaces and form a biofilm within days of the leaf's entry into
a stream environment. Experimental mineralization of fresh and biofilm-coated
leaves indicates that leaves without biofilm do not mineralize, but leaves
with biofilms rapidly adsorb metal ions such as Fe3+ onto the anionic biofilm
surface where the ions form ferrihydrite. Once these mineralized leaves are
buried by the sediment, they are more likely to be converted to fossils than
non-mineralized leaves. Examination of a fossil leaf surface by scanning
electron microscopy shows bacteria-sized structures resembling those found in
biofilms. These experimental data imply that bacterial colonization of leaves
may be an essential prerequisite for authigenic preservation."~K. A. Dunn, et
al, "Enhancement of Leaf Fossilization Potential by Bacterial Biofilms,"
Geology 25(1997):12:119-1222, p. 1119
"Under normal circumstances, leaves and other plant detritus are
colonized and decomposed by a variety of microorganisms and
macroinvertebrates. However, decay of whole plant organs such as leaves can
take as long as months to years, which provides a window of time during which
fossilization can occur. The caliber of leaf fossils is greatly enhanced if
mineralization can commence before much decomposition can occur."~K. A. Dunn, et
al, "Enhancement of Leaf Fossilization Potential by Bacterial Biofilms,"
Geology 25(1997):12:119-1222, p. 1119
"Platanus leaves placed in the San Marcos River for five days were
colonized by a fiofilm of naturally occurring bacteria containing 10^7
colony-forming units (CFU) per square centimeter of leaf surface. These
organisms were not fully identified but consisted primarily of Pseudomonas sp.
and other gram-negative rods. In contrast, fewer bacteria (<10^2 CFU
persquare centimeter) were present on freshly picked platanus leaves."~K. A.
Dunn, et al, "Enhancement of Leaf Fossilization Potential by Bacterial
Biofilms," Geology 25(1997):12:119-1222, p. 1120
"When the biofilm-containing Platanus and Taxodium leaves were placed into
either 10mM FeCl3 or 300 ppm silica, a color change indicating mineral
formation was readily observed within 5-10 min. Examination of the leaf
surfaces by SEM confirmed the presence of mineral formation in the presence of
biofilms. No mineral formation was observed in the leaves without a biofilm,
even after six weeks of incubation."~K. A. Dunn, et al, "Enhancement of Leaf
Fossilization Potential by Bacterial Biofilms," Geology
25(1997):12:119-1222, p. 1120
"Examination of some iron-encrusted fossil leaves shows evidence for both
rapid precipitation of iron at the leaf surface and structures of probable
bacterial origin. both are well-illustrated by leaves of Nelumbrites minimus,
an aquatic angiosperm from the Lower Cretaceous Potomac Group of Virginia and
Maryland. Iron-encrusted leaves of N. minimus can show fine scale surface
detail including vein course, epidermal cell outlines, shallow doming of
epidermal cells, and stomata. In addition, smaller-scale features of probable
bacterial origin are present on the surface. These include 1-2 microm
structures resembling bacterial cells and material resembling a dehydrated
biofilm matrix."~K. A. Dunn, et al, "Enhancement of Leaf Fossilization
Potential by Bacterial Biofilms," Geology 25(1997):12:119-1222, p. 1120
"Spicer noted that leaves in modern depositional settings can develop an iron
encrustation within a few weeks of their entry into a stream depositional
system. Iron-bacteria in particular Spaerotilus sp., were present on leaves
examined from England, and were proposed as the primary means of iron
encrustation."~K. A. Dunn, et al, "Enhancement of Leaf Fossilization
Potential by Bacterial Biofilms," Geology 25(1997):12:119-1222, p. 1121
Now, the fact is that this is similar to how fish fossils form. I
remembered an article that I had read several years ago, so I looked it up
tonight.
"Microbial mats are one of the factors most widely invoked
to explain exceptional fossil preservation. They are believed to
prevent carcasses from floating and to protect them from
scavengers and currents. Microbial mats may also be sites of
rapid mineralization, perhaps because they create localized
oxygen-minimum environments."~Philip R. Wilby et al, "role of
Microbial Mats in the Fossilization of Soft Tissues," Geology,
Sept. 1996 24:787-790, p. 787
Thus, it would appear that, contrary to the creationist claims that fossils
require immediate burial, fossil fish need a little time unburied so that
the bacteria can form a mineral covering.
glenn
Adam, Apes, and Anthropology: Finding the Soul of Fossil Man
and
Foundation, Fall and Flood
http://www.isource.net/~grmorton/dmd.htm