6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 91 



Overlying the Price Kiver formation, apparently in conformable 

 relation, is the fossiliferous series of clays, sandy clays, and sand- 

 stones that have been designated by Spieker as the North Horn forma- 

 tion. The use of this name should in the opinion of the writer have 

 been restricted so as to include only the Cretaceous or Paleocene 

 beds and not both. However, since the U. S. Geological Survey has 

 adopted the more inclusive definition for North Horn, the name Joes 

 Valley is proposed as a member to include the Paleocene portion of 

 the North Horn formation. The clays and sandy clays in the Creta- 

 ceous portion of the North Horn are varied in color with thick beds 

 of gray, green, and brown shades of clay with occasional thinner 

 zones of more reddish clay. Near the top the buff sandstones become 

 more conspicuous, forming cliffs below the Paleocene deposits. 



The Joes Valley member exposed high on the mountain slopes 

 adjacent to Joes Valley has been more critically observed farther 

 south on North Horn Mountain, and particularly in Dragon Canyon, 

 where the Paleocene fossils occur. The member is defined as begin- 

 ning with the highly colored clay and sandy clay, locally black 

 carbonaceous shales, resting abruptly but without apparent discon- 

 formity on the massive sandstones capping the dinosaur-bearing 

 North Horn beds. The variegated clays of the Paleocene series re- 

 semble those in the lower portion of the North Horn formation but 

 are usually not so thick and appear to be more gaudily colored and 

 with conspicuous white channel sands. The upper portion of the 

 Joes Valley member, above both of the fossil levels, is not so markedly 

 variegated and includes a greater quantity of buff sandstone, with 

 thicker zones of more uniformly colored sandy clay, ending abruptly 

 beneath the Flagstaff limestone. The thickness of the Joes Valley 

 member was not measured, but it clearly amounts to several hundred 

 feet. Apparently, however, it is not so thick as the lower portion of 

 the North Horn. 



The Flagstaff limestone, overlying the Joes Valley member, contains 

 numerous fresh-water shells, but it has produced no vertebrate re- 

 mains. Its age is not certainl}^ determined, but it may be within 

 the limits of the Paleocene. Overlying the limestone in various 

 places in Dragon Canyon is a series of soft clays that on weathered 

 surfaces show brick red alternating with much lighter colors. Inter- 

 bedded with the clay are occasional thin beds of limestone. This 

 material is designated on the map as post-Flagstaff. No fossils 

 were found in these beds. 



Structure. — Dragon Canyon is essentially part of a graben that 

 extends a considerable distance north and south. The downdropped 

 block is highly faulted and amounts simply to a zone of faulting in 

 which the slices are all depressed below the relatively undisturbed 



