282 
They were collected by John L. James 
and given to Frank L. Hess, formerly 
of the United States Bureau of Mines, 
who made them available to me for 
study and conferred with me in the 
preparation of this paper. The speci- 
mens are silicified and the wood, which 
is coniferous, shows evidence of exten- 
sive destruction before being covered 
with algalincrustations. Anotherspec- 
imen (pl. 7, fig. 1) is from a locality 
near Eden and Farson in the valley of 
Sandy Creek, 25 miles northeast of 
Whisky Basin, but from the same 
Bridger strata. This area is noted for 
“geyser cones’ and fossil wood. The 
wood of this specimen is dicotyledon- 
ous, probably of the sumac family 
(Anacardiaceae), 
During many millions of years the 
present drainage system evolved in the 
Bridger Basin, carving low hills and 
broad valleys out of the Green River 
and Bridger strata and exposing the 
long-buried algal pillars. These now 
remain as monuments marking sites 
along the shores of the Eocene lakes 
where timber was submerged, covered 
with algal deposits, and then, for the 
most part, destroyed without a trace. 
It is unlikely, however, that all such 
pillars originated precisely in the 
manner just described, for algae could 
settle on other objects than wood at 
the bottom of a lake and thus produce 
variations in the process of pillar and 
reef building, with subsequent com- 
plications. 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
The hollow “sand trees,’ recently 
described by Walker (1948) from San 
Nicolas and San Miguel Islands off 
the southwest coast of California, were 
formed in an entirely different man- 
ner, namely, by burial of trees in wind- 
blown sand, with subsequent rotting 
of the trees and mineralization of the 
peripheral casings by calcite. 
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ALLEN, EUGENE T. 
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Brapiey, Witmot H. 
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Coup, Preston E., Jr. 
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Howe, MarsHALL A. 
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Jounson, J. Haran. 
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