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 clifTs 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 



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Fig. I. — 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. i. Here bed i 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 i 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 i 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. 



