Dr. Arnold Guyot,
Director of the E. M. Museum.
INTRODUCTORY NOTE
UPON THE
GEOLOGY OF THE BRIDGER BASIN.
Fort Bridger is a government military post, situated on the high southern plateau of western Wyoming Territory, in the midst of one of the most interesting geological regions of the world.
The country on all sides was once the bottom of a great eocene lake, the water of which was probably slightly brackish. Whether this lake district had direct communication with the ocean, is undetermined as yet, but there is a possibility that it had.[1]
[1] Ichthyic fauna of the Green River shales, Hayden's Surveys, vol. iii., No. 4, p. 819.
The tributaries of the Green River, which drain this plateau, render the valleys along the edges of the streams green and wooded. Beyond this fertile strip, wide, barren plains extend, covered by a dense growth of short "sage brush" (Artemisia tridentata).