328 Annals of the Carnegie Museum. 



ties in the same formation it has thus far been found quite difficult to 

 establish definitely the relative positions of such horizons within the 

 same formation. 



On visiting the bone (quarries near Canyon City, Colorado, made 

 classic by the researches of the late Professors O. C. Marsh and E. D. 

 Cope, in the spring of 1900 shortly after taking charge of the Depart- 

 ment of Vertebrate Paleontology in the Carnegie Museum, the striking 

 advantages presented by this locality not only for collecting the remains 

 of dinosaurs, but for determining the exact stratigraphic position of 

 the various skeletons both with reference to each other and to the 

 underlying Trias and overlying Cretaceous formations were at once ap- 

 parent. 



Perhaps in no other locality is the geological section from the base 

 of the Trias to the top of the Cretaceous more complete than in the 

 canyon of Four Mile, or Oil Creek, from the entrance to Garden Park, 

 some eight miles east by north of Canyon City to the mouth of that can- 

 yon where it opens into the valley of the Arkansas River and thence 

 across the valley to the foothills on the south side of the river, on a 

 line about midway between the towns of Canyon City and Florence. 

 The geological section along this line is remarkably complete and ex- 

 ceptionally well displayed, so that in passing down Four Mile Creek 

 through Garden Park and the somewhat rugged canyon through which 

 the creek flows on its way from the Park to the valley of the Arkansas 

 River and thence across the river valley to the hills back of Florence 

 there may be seen a continuous section commencing below with the 

 brick red Triassic sandstones which form so conspicuous a feature in 

 the bluffs on the west side of Garden Park and terminating above in 

 the yellowish brown Laramie sandstones and Denver Beds of Cross 

 and Eldridge found capping the bluffs and lower foothills On the south 

 side of the Arkansas River. A brief description of the more important 

 horizons shown in this section may not be out of place. 



The Triassic. 

 To the Trias I refer the red sandstones just alluded to as so con- 

 spicuous in Garden Park. I have placed these sandstones in the Trias 

 rather than the Carboniferous on no direct paleontologic evidence, but 

 rather on account of their general resemblance to the red sandstones, 

 which in other places underlie the Jura, and have by common consent 

 been considered as belonging to the Trias. Dr. Whitman Cross has 



