THE BOULDER, COLO., OIL FIELD. 
By N. M. Fenneman. 
INTRODUCTION. 
For many years the rocks near Boulder have been popularly sup- 
posed to contain petroleum. The basis of such rumors lay partly in 
the strong bituminous odor of certain rocks and partly in certain 
cases of seepage known as "oil springs." Reports based on the 
former can be traced back to 1867, at which time the black Benton 
shales were dug into in search of coal. Their evident bituminous 
character led Mr. Joseph Wolff and others about ten years later 
to attempt the formation of an oil company, with the intention of 
drilling near the center of the present developed field. The proposed 
location at that time was determined by going straight east from the 
excavations in the upturned Benton of the foothills to a point on the 
plains where it was supposed the same strata might be horizontal. 
The project failed for lack of funds. 
The oil springs which have been reported lie north of this area, the 
one best known being on the Culver ranch on the north bank of the 
Little Thompson, 17 miles north of Boulder and several miles east of 
the foothills. Here, at the base of the heavy sandstone stratum in 
the Pierre (mentioned below), a seepage of oil has been observed for 
forty j^ears. Several similar but less-known occurrences are reported 
from 5 to 10 miles north of Boulder. 
In 1892 a well was drilled on Gunbarrel hill, 1 mile north of Boulder 
Creek and 7 miles east of the foothills. Accounts of this well are 
very conflicting. Sufficient encouragement seems to have been 
obtained from this attempt to keep alive the idea that future efforts 
in the vicinity would develop a producing field. 
Upon the renewal of interest in 1001 the Boulder Oil Company was 
organized through the efforts of Mr. Isaac Canfield and Mr Charles 
Page. The McKenzie well was drilled by this company. This well 
struck oil in January, 1902, since which time many companies have 
been organized and the exploiting of the field has proceeded without 
interruption. 
The exact location of most wells has been determined by "bobbers." 
Rumors ascribe to Hayden various utterances on the subject of oil, 
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