The Specimen Creek fossil forests in Yellowstone National Park show up to
fifty layers of fossil forests with upright trees. The conventional
explanation is that each new forest grew atop the previous ones as the
previous forests were buried in volcanic ash. This explanation fails;
instead, the fossil forests result from the deposition of trees uprooted
from elsewhere.
Specimen Creek and the surrounding area show evidence of some trees
transported and others buried in place. The rock layers include
conglomerates from meandering and braided streams, conglomerates from
mud flows, and tuffaceous sandstones composed mostly of
water-transported volcanic ash. In the Eocene, the area would have
been between two volcanic chains. Occasional mud flows from the slopes
of the mountains would have uprooted and transported trees from the
slopes and buried lowland trees in place (Fritz 1980; 1984).
Evidence that some of the trees, especially those on Specimen Ridge,
were buried in place, includes the following (Retallack 1981; Yuretich
1984a; 1984b):
There are tree stumps that are rooted in fine-grained tuffaceous
sandstone but buried in conglomerates.
Upper parts of some stumps and logs, surrounded by conglomerates,
were severely abraded, but the lower parts in sandstone have good
root systems.
Flow structures in some conglomerates show they buried in-place
trees.
Thin sections show evidence of soil around the roots.
There are clear soil horizons around some root systems.
Most of the horizontal logs and some stumps (up to 15 percent of the
upright stumps, according to Fritz 1984) were transported, but most of
the upright Specimen Ridge fossil trees were buried in place.
Upright stumps and trees on Specimen Ridge cannot be explained as
floating stumps settling out of standing water, as proposed by Coffin
(1983) based on observations of trees washed into Spirit Lake.
Most tree fossils in Yellowstone occur in sediments from high-energy
flows, not a low-energy lake environment (Fritz 1983).
The percentage of erect trees in Yellowstone is more than 50 percent
on Specimen Ridge, but only about ten to twenty percent of trees
stay upright in flows such as in Spirit Lake (Fritz 1983).
Many of the Specimen Ridge trees are rooted in soils, as noted
above.
References:
Coffin, H. G., 1983. Erect floating stumps in Spirit Lake, Washington.
Geology 11: 298-299.
Fritz, W. J., 1980. Reinterpretation of the depositional environment of
the Yellowstone "fossil forests". Geology 8: 309-313.
Fritz, W. J., 1983. Comment and reply on "Erect floating stumps in
Spirit Lake, Washington." Geology 11: 733-734.
Fritz, W. J., 1984. Comment and reply on "Yellowstone fossil forests:
New evidence for burial in place." Geology 12: 638-639.
Retallack, G., 1981. Comment and reply on "Reinterpretation of the
depositional environment of the Yellowstone fossil forests". Geology
9: 52-53.
Yuretich, R. F., 1984a. Yellowstone fossil forests: New evidence for
burial in place. Geology 12: 159-162.
Yuretich, R. F., 1984b. Comment and reply on "Yellowstone fossil forests:
New evidence for burial in place." Geology 12: 639.
