Algal Pillars Miscalled Geyser Cones’ 
By Roianp W. Brown, Geological Survey, U. S. Department of the Interior 
[With 8 plates] 
The unsuspecting traveler on the less- 
frequented trails in the region north- 
west of Rock Springs and Green River, 
Wyo., may occasionally be surprised 
and mystified by encountering what 
seem to be either fossil stumps or 
rounded rock columns erected by a 
prehistoric race. At a number of lo- 
calities these protrude through the 
strata as large conical or cylindrical 
pillars, standing singly or in small 
groups (pls. 1, 2). Local collectors 
have dug out many of them, which 
they, as well as some geologists, have 
tentatviely called geyser cones, that 
is, vertical, hollow structures resem- 
bling those developed at the vents of 
hot springs and geysers. Superficially, 
this identification has some plausibility 
because many of these pillars are more 
or less hollow and cross sections of 
them display layered deposits some- 
what like those present in most geyser 
cones. However, here, as elsewhere, 
appearances are deceptive, things are 
not what they seem, and hasty con- 
clusions based on only a few of the 
most obvious features of the circum- 
stantial evidence must be revised. 
Herewith are the details of my own 
adventures and observations regarding 
these objects. 
During field work in the summer of 
1946, I arrived one day at Green River, 
Wyo., and became acquainted with 
William Hutton, Jr., an enthusiastic 
collector. The elaborate ‘‘den’’ in the 
1Published by permission of the Director, 
U. S. Geological Survey. 
basement of his home contains an ex- 
hibit of his large collection of minerals, 
rocks, fossils, and archeological relics. 
Attracting immediate attention is the 
wall of the spectacular fireplace, which 
is constructed largely of fossil wood, 
but mixed with the wood are sections 
of ‘“‘geyser cones.” These, together 
with the hundred or more additional 
specimens around the outside of the 
house and along the walks in the yard, 
aroused my curiosity intensely. Not- 
ing this, Mr. Hutton volunteered to 
accompany me to a nearby locality 
where I could see “‘geyser cones’’ in 
place and observe attendant geologic 
conditions. Thus, Sunday morning, 
September 15, found us in Whisky 
Basin, a local part of the larger Bridger 
Basin. The locality is a high, open 
valley area surrounded by low, bad- 
land hills, about 27 miles northwest of 
Green River and 12 miles northeast of 
Granger (pls. 1, 2). A locality similar 
to this, but not visited by me, is 30 
miles west of Whisky Basin and 6 to 8 
miles southwest of Opal, Wyo., where 
G. P. Merrill, in 1903, collected many 
specimens for the United States Na- 
tional Museum. Sections of some of 
these are here illustrated as noted in 
the legends. 
The rock strata of the valley floor 
and surrounding hills are nearly hor- 
izontal, variegated, but chiefly green- 
ish sands and clays having a heavy 
admixture of volcanic ash. There 
are occasional lenses of ironstone and 
carbonaceous shale. These strata lie 
277 
