obous.] MANITOU TO DENVER. 435 



concealed by the Tertiary strata which abut against the foothills. On 

 the northern side of the divide the road again diverges from the foothill 

 line and passes rapidly down into the valley of Plum creek, which it 

 follows to the Platte river. The. most striking feature of the landscape, 

 for a considerable distance, is the number of isolated flat-topped buttes, 

 which are made up of Monument Creek strata with, in many cases, a 

 capping of pinkish rhyolitio tuff, a rock much used as a building stone 

 in Denver. These buttes are specially well shown in the vicinity of 

 Larkspur, Douglas, and Castle Rock. The quarries from which the 

 tuff is obtained are near the last two stations. In Castle Eoek, a small 

 hill with abrupt cliffs at the top, is evidence of an erosion which fol- 

 lowed the tuff deposition, and indicates a division line in the Tertiary 

 series, the importance of which has not yet been demonstrated. Ter- 

 tiary beds extend somewhat farther north than is represented by the 

 Ilayden ma]), and it is not until within a short distance of the Platte 

 river that the underlying beds are exposed. 



Below Sedalia the line of upturned strata following the mountain 

 base becomes again visible, and the Dakota hogback in particular can 

 be traced for miles. Shortly before reaching Acequia a huge irriga- 

 tion ditch is crossed, by which water from the Platte is conducted to 

 the dry plains immediately east of Denver. Opposite Acequia is seen 

 the gap through which the Platte river issues from the mountains. 

 From the mouth of Plum creek to Denver the route passes over the 

 two post-Laramie formations — the Arapahoe and the Denver — which 

 will be referred to in detail below. 



DENVER. 

 By Whitman CBOSS. 



In 1859 the first log house was built where Denver now stands. In 

 1870 the city had 4,730 inhabitants; in 1880,35,628; in 1800, about 

 1 40,000. In its business blocks, theaters, school buildings, and pri- 

 vate residences Denver stands on a par with many older Eastern cities 

 of a larger population. 



The city is built on slightly terraced plains, along either bank of the 

 South Platte river, at about 10 miles from the mountains. From a 

 favorable point the observer commands a magnilicent view of the Front 

 range of the Rocky Mountains, extending from , the northern line of 

 the State southward to Pikes Peak, a distance of 150 miles (240 km.). 

 The most prominent peaks visible from Denver are, commencing at the 

 north, Pongs Peak (14,271 feet— 4,350 m.); Grays Peak (14,341 feet— 

 4,371 m.); Mount Evans (14,330 feet— 4,308 m.), and Pikes Peak 



