THE DENVER SHORE-LINE. 183 



indicated the shore-line; but in the angle between (Mem- ('reck and the 

 Platte Riyer, in the low hills a mile or more hack from these streams, 

 remnants of the Denver are found resting on the Arapahoe in positions 

 showing a very uneven sea-bottom, and suggesting the proximity of the 

 northern shore-line of Arapahoe land. The details of this region are 

 derived chieflv from Mr. Eldridge's notes, for these Denver exposures were 

 discovered by him while studying the Arapahoe. 



It is impossible to indicate upon the map the details of the relation 

 between the two formations as it is here known. The generalization of the 

 map niav he explained in words by saying that these hills are capped by 

 thin remnants of the Denver beds at varying altitudes, through which many 

 of the small drains have cut into the underlying Arapahoe; mid that, as 

 practical horizontality exists for both formations as a whole, the elevation of 

 the Arapahoe floor at this 'point, being some 200 feet above the known 

 Denver beds on Clear ('reek near its month, necessitates the conclusion 

 that the north shore of the Denver Basin was rapidly ascending in the area, 

 in question. Moreover, the still higher ground occupied bv the Arapahoe 

 to the northward seems to show the form of the Denver sea-bottom in 

 this direction. 



The southern shore-line deposits. East of tll6 Platte Plivei* Mild Ileal' the aSceiul- 



ing line of the Arapahoe as it approaches the Monument ('reek there are 

 some exposures of Denver strata which clearly show the immediate prox- 

 imity of the old shore-line. On one of the creeks, just about the High- 

 Line Canal crossing, are several good outcrops on sloping gulch hanks, of 

 very light-colored sandstones or grits, coarse and crumbling, in which no 

 eruptive material can he found. These light-colored beds lie in isolated 

 patches, while above, below, and, in some cases, between them, are typical 

 Denver beds, rich in dark, eruptive-rock pebbles. Taken by itself this 

 group of outcrops would be accounted for with difficulty, but a short 

 distance up the same creek on the north bank is a bluff outcrop in which 

 the explanation for this occurrence is well shown. Here are seen grits 

 composed of quartz and feldspar, overlain and underlain by normal Denver 

 heils, and these grits are seen to pass laterally in continuous outcrops 

 into beds of nearly the same grain in which andesitic pebbles are abundant 



