XVIII. THE AGATE SPRING FOSSIL (,)UARRY. ' 

 By O. a. Peterson. 



In 1904 a field i)arty of the Carnegie Museum, the writer in charge, 

 was extremely fortunate in discovering what will undoubtedly prove 

 to be one of the most important quarries of fossils as yet discovered in 

 the Miocene of North America. Geographically the (juarry is located 

 on the Upper Niobrara River, locally known as the " Running 

 Water," in Sioux County, Nebraska. It is about twenty-five miles 

 southeast of Harrison, a station on the Fremont, Elkhorn, and Missouri 

 Valley Railroad. 



The geological horizon in which the (juarry is located is at the base 

 of the Nebraska'-' Beds, or the top of the Harrison Beds. 



In 1890 Mr. James H. Cook, on whose property the Agate Spring 

 Fossil Quarry is located, discovered many small bones and fragments 

 in the talus from the fossil-bearing stratum of the hills, in which the 

 quarry is located. Very naturally he thought that the bones were 

 those of Indians interred together with their horses. Mr. Cook ac- 

 companied me to this place in August, 1904. Realizing that this was 

 a discovery of much paleontological promise we immediately began 

 work on the deposits and resumed work early in the season of 1905. 



The quarry is about one quarter of a mile south of the river referred 

 to above. It is near the base of two closely connected and rounded 

 buttes, which have been separated by erosion and in part covered by 

 vegetation. These hills are composed of a buff-colored sandstone vary- 

 ing in degrees of hardness. A layer of about three or four feet in 

 thickness, including that of the fossil -bearing stratum, is of a rather 

 light color. The strata in this immediate vicinity, including that of 

 this fossil quarry, have a slight dip northward. Immediately under 

 and overlying the fossil-bearing stratum there are layers of compact 



' Read before tlie American Society of Vertebrate Paleontologists, December 27, 



1905- 



^ Scott, Bull. Geol. Soc. Am., Vol. V., pp. 595-596, 1893. Hatcher, Proc. 4 in. 

 Philos. Soc, Vol. LXI., pp. 117-118, 1902. Peterson, An.n. Carnegie Museim, 

 Vol. II., pp. 473-474, 1904. Darton, U. S. Geol. Survey, " Geology and Under- 

 ground Water Re.sources,"' pp. 177-178, 1905. 



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