274 
ELDRIDGE. 
curve may at times be complete within a distance of fifty 
feet. A fault is, therefore, unnecessary to explain the abrupt 
change from the vertical to the horizontal position. More¬ 
over, observations show that the Denver and Arapahoe beds 
actually take part in this fold at a point directly opposite 
South Table Mountain. The complicated geology of the 
region would very naturally lead one to mistaken conclu¬ 
sions unless a thorough knowledge was possessed not only 
of the area of disturbance here considered, but also of the 
general structure of the region far beyond. The fourth 
point in the quoted remarks of Professor Ward relates to 
the manner in which he accounts for the fossil Mactra found, 
according to prior statements, “over” the coal. As a matter 
of fact, the fossil does not occur over the coal, but beneath it, 
in its usual position in the Fort Pierre bed, its apparent posi¬ 
tion being due to lying within a locally faulted area, the beds 
of which have been thrown to the eastward of the general 
trend of the coal in the unaffected area to the south and 
north. 
The views of Others .—In addition to the views of the above 
gentlemen, others have from time to time been expressed, 
implying belief in a fault in the vicinity of Golden to ac¬ 
count for the peculiarities of structure there displayed. In 
reply to this it need only be stated that no fault can be con¬ 
ceived which will at once account for the several features in 
the geology of this region as exposed over the present sur¬ 
face of the area and set forth in the preceding pages of this 
article. 
