A Fossil Araucarian Wood Fro Western Wyoming

Abstract

A few years ago the senior author made a collection of silicified woods from the Gros Ventre Canyon in western Wyoming. We were attracted to the region partly by some petrified log fragments on display outside the Jenny Lake Post Office, which were said to have been collected in the canyon, and partly by a landslide that presents a conspicuous scar on the lower end of the canyon, a landmark readily seen from the vicinity of Teton Park. Although two visits to the slide area failed to reveal anything of paleobotanical interest, certain regions farther up the canyon proved more productive. Approximately twelve miles up the road there is a second and considerably older slide now partially concealed by a fairly heavy vegetation. When this older landslide occurred the Gros Ventre Canyon was blocked and a lake formed in Cole Hollow. At the time of our 1936 visit a petrified trunk some three feet in diameter was exposed approximately 200 yards from the south bank of the river. The slide area was subsequently followed up to its apparent origin, a point about one mile from the river (Mt. Leidy quadrangle, R 112 W, T 42 N). There, a small badlands area, some few acres in extent and light gray color, is quite prominent when viewed from the opposite side of the valley. Sections of silicified trunks and small twigs are comparatively abundant in the gullies, weathering out of rocks of Cretaceous age. A more precise determination of the horizon is not possible at present, since neither the stratigraphy nor paleontology of the region has been studied in detail. Very small-scale coal-mining operations have been carried out on the opposite side of the river, likewise in Cretaceous strata. A seam some four feet thick outcrops about one-half mile north of the river and has been exploited in the past. The seam includes a number of bands of sandy clay some of which contain fern and dicot