ECOLOGICAL SIGNIFICANCE OF EAGLE CREEK FLORA 581 
Collections of leaf impressions were made in eighteen localities, 
ranging from the mouth of Moffatt Creek on the Oregon side of the 
gorge to the foot of the cliffs at Red Bluffs in Washington, six miles 
distant. These collections, while made up of rather fragmentary 
material on the whole, include remarkably well-preserved leaves 
where the matrix is a fine clay. In most situations the leaves 
were secured just above a layer of carbonaceous shale which 
represents the old soil line, in the fine sandy or shaley material laid 
down upon the old surface. 
The following description of a locality on the Columbia River 
Highway shows the typical occurrence of the fossil plants: 850 feet 
Fic. 1.—Section of the Eagle Creek formation 850 feet west of the Tanner 
Creek bridge on the Columbia River Highway, showing relations of the soil line and 
the upright tree. 
west of the Tanner Creek bridge on the Columbia River Highway, 
a bed of cobble conglomerate 20 to 25 feet in thickness is overlain 
by a carbonaceous seam containing leaves. The general relations 
are shown by Fig. 1. Here bed 1 is a layer of coarse conglomerate 
which is overlain by bed 2, a seam of carbonaceous sandy shale 
from 8 inches to 3 feet in thickness. Overlying bed 2 and inclosing 
the fossil tree which is rooted in the shale is bed 3, comprising 15 feet 
of sandstone containing numerous bowlders. 
The upper surface of 1 is suggestive of an erosion surface on 
which several feet of soil 2 accumulated. The upright tree 
appears to have been growing in a valley cut in 1 during the time 
of the soil accumulation, and about its roots numerous leaves have 
been buried and fossilized.! The lack of another slope makes the 
« A microscopical examination of this fossil wood has not yet been made to deter- 
mine its taxonomic relations. 
