On 11 Feb 97 at 22:24, Glenn Morton wrote:
> The evidence on the Yellowstone forests is equivocal. If a volcano blew up,
> most of the trees would be felled by the shock wave as happened at St.
> Helens. Most of the trees are horizontal at the yellowstone forests.
> Horizontality does not necessitate that the trees were transported from far
> off.
I would like to explain briefly why I think the Yellowstone
"Fossil Forests" are not the remains of buried standing forests.
This model was developed by Dorf (1964) and was widely accepted.
A persuasive reinterpretation was presented by Fritz (1980a,
1982) who had worked on these rocks for his MS and PhD research.
Although Fritz's research stimulated vigorous discussion, I
consider that Fritz had the better of the exchanges.
"Processes operating in the proposed depositional environment
produced a complex series of sedimentary rocks ... where no
"forest" or layer cake exists that can be traced for any
distance. Thus, a layer cake model depicting continuous layers
of even thickness alternating between air-fall tuff and breccia
with 95% of the trees vertical (counts taken from Figs. in Dorf
1960, 1964, 1964b, 1974, 1980) is not valid. Instead a complex
typical alluvial deposit is present consisting of lenses, rapid
facies changes and non-continuous layers" (Fritz, 1982, p.95).
Both Fritz (1980b) and Coffin (1983) found the Mt St Helens
eruption to be a modern analogue for some of the processes
involved at Yellowstone - notably the presence of transported
upright trees with rootlets.
As a more general comment, I regard the Yellowstone "forests" as
a good example of how contrasting paradigms in geology make
people sensitive to different types of data. Dorf represents the
Lyellian tradition, whereas Fritz (and Coffin) represent neo-
catastrophism. (Neo-catastrophists do not say that everything
is catastrophic, but they are far more open to the rock record
being linked to catastrophic processes - and they do seem to find
much more evidence for catastrophism than the Lyellians!)
References:
Coffin, H.G. 1983. Erect floating stumps in Spirit Lake,
Washington. Geology, 11(May), 298-299.
Dorf, E. 1964. The petrified forests of Yellowstone Park.
Scientific American, 210(4), 106-114.
Fritz, W.J. 1980a. Reinterpretation of the depositional
environment of the Yellowstone "fossil forests". Geology,
8(July), 309-313.
Fritz, W.J. 1980b. Stumps transported and deposited upright by
Mount St. Helens mud flows. Geology, 8(December), 586-588.
Fritz, W.J. 1982. Geology of the Lamar River Formation,
northeast Yellowstone National Park, in Reid, S.G. and Foote,
D.J. eds, Geology of Yellowstone Park area: Wyoming Geological
Association Guidebook, 33rd Annual Field Conference, 73-101.
GlennM:
> There is an interesting article I ran into concerning the fossil
> forest. It is Richard M. Ritland, Stephen L.
> Ritland, "The Fossil Forests of the Yellowstone Region," Spectrum, No. 1/2,
> 1974.
It seems to me that all the points raised here are not inconsistent
with Fritz' model.
I'm very behind with my email at present. I know there are others on
this topic. I want to come back on some of Glenn's other feedback on
Joel's post - next week!
Best wishes,