116 ANNALS NEW YORK ACADEMY OF SCIENCES 



dinosaur quarry. It has been noted by Dr. H. E. Gregory' in the south- 

 western areas in beds 300 feet or more in thickness. 



Clianneling is an especially characteristic feature of the Morrison for- 

 mation. It is widespread and occurs on both large and small scales. 



Tbinning out of individual beds is common, when erosion channels may 

 not be visible to the eye. 



Several of these features are well shown at the dinosaur quarry worked 

 by Professor 0. C. Marsh's collectors, and later by Mr. J. B. Hatcher for 

 the Carnegie Museum. The quarry is situated on the north bank of a 



Fig. 81. — Type of cross-bedding usually known as the stream type. 



small gulch which empties into Oil Creek, about eight miles north to 



northeast of Canon City, Colorado. The beds for a short distance above 



and below the level of the quarry are well shown on both sides of the gulch. 



The section of the Morrison in the vicinity of the quarry is as follows : 



Feet 



"Variegated clays 



White sandstone 5 est. 



Bone-bearing sandstone, coarse, calcareous, somewhat arkosic, with 



grains of volcanic material 3 



Strongly cross-bedded sandstone at the floor of the quarry 5 



Clay (absent at the quarry but present on the opposite side of the 



gulch) 1 — 



Sandstone, white, fairly coarse 2 to 15 



Clay with nodule layers 



^ Personal communication. 



