EXTENT OF THE DENVER. 185 



;it the northwestern extremity <>l the present area of these rocks, the lower 

 450 to 500 feel of the formation is now protected by the basalt sheets 

 which were poured oul upon tii<-ni during the Denver epoch. North Table 

 Mountain possesses an average elevation above the adjacent country 

 of 650 i" 800 feet; its basall capping presents cliffs varying in heighl from 

 luu to 200 feet, and belowthem are rather steep slopes upon which here 

 and there over ili<- entire extent of the mountain are outcrops of Denver 

 strata. So far as known they are horizontal <>r have possiblj ;i very slighl 

 <li|t to the southeast. The soft, easily disintegrated sandstones and <-l;i\s 

 afford projecting outcrops < >n ] \- under tli<- most favorable circumstances, 

 hence the slopes are unusually ddbris-covered, bul \\ here smooth, a blow of 

 the ]ii«'l< will commonly expose the sandy <>r clayey strata. 



The contact of the main basaltic sheel with the Denver strata is 

 exposed in many places at the base of the cliffs, ;m<l the relation of the 

 smaller, earlier basall streams t" lli«- inclosing sandstones is clearly shown* 

 The former contaci is particularly well exhibited a1 the head of the south- 

 ern gulch which cuts into the mountain; also on the southern face between 

 the large gulches, on the western side of the larger gulch, and on the 

 northwestern face above the eastern end of the lower basall flow. Below 

 the last contact and al several places upon the southern slopes are outcrops 

 of strata at \ arious horizons. 



The actual line between the Denver and the underlying Arapahoe beds 

 is nowhere visible. From the data soon to be given ii is estimated that 

 the thickness of the Denver strata present below ili«- l>;is;ilt can nol be far 

 from 450 tn IT.'i feet. The base of the formation along the northern fool of 

 Table Mountain is drawn according to the estimate, with the assumption 

 that there is a slight easterly dip to the strata. Directly west of North 

 Table Mountain the rising ground and nearness to the great fold require 



that the Denver beds should takes ipart in the fold, and the yellowish, 



Bandy strata which are imperfectly seen in the southern end of the railroad 

 cutting do appear to have an easterly dip of 20 to 25 . These strata are 

 thoughl t" be near the base of the Denver series, although by no means of 

 characteristic composition. 



South Table Mountain, although lower, exhibits much better exposures 



