MOOK, STUDY OF THE MORRISON FORMATION 41 



data gathered for use in the above-mentioned monograph. Conferences 

 have been held with Professors A. W. Grabau, C. P. Berkey and J). W. 

 Johnson, of Columbia University, who have made suggestions in regard 

 to the work. Messrs. W. T. Lee, JST. H. Darton, W. Cross and C. T. 

 Lupton have added data regarding the distribution of the Morrison in 

 the southern areas, and the director of the United States Geological Sur- 

 vey has given permission to use these unpublished data, and to use the 

 map which was redrawn by Survey draughtsmen from an original by the 

 writer. Valuable information has also been given by Mr. S. H. Knight, 

 of Columbia University. 



Definition of Formation 



The name Morrison was first applied to the series of deposits under 

 discussion, by Cross, in the Pike's Peak folio of the United States Geolog- 

 ical Survey.' It was proposed to include the series of clays, sandstones 

 and shales which underlie the Lakota-Dakota series and overlie a white 

 sandstone, which in turn rests on the Eed Beds, at the village of Morrison, 

 nearly west of Denver, Colorado. The names "Jurassic Beds," "Dakota 

 Beds," "Variegated Beds," "Beulah Shales," "Atlantosaurus Beds," 

 "Como Beds," "Gunnison Formation," "McElmo Formation" and "Flam- 

 ing Gorge Formation" have all been applied to beds in various regions 

 in a general way equivalent to the Morrison in eastern Colorado, though 

 in some cases these terms have included more than the typical Morrison. 



The name Morrison has been used extensively in the publications of the 

 United States Geological Survey for this formation in other areas than 

 the original area in eastern Colorado. As it was the first geographical 

 name applied to the formation, it may be used as the valid formation 

 name for the deposits concerned. In the present paper it will be used 

 for the areas in western Colorado and Utah, where the beds have been 

 known as Gunnison, McElmo, and in part Flaming Gorge, as well as for 

 the more eastern representatives. The local names are often convenient, 

 however, to designate the formation in particular localities. 



The series is composed essentially of beds of variegated clays or marls, 

 often described as "joint-clays," sandstones and shales, with minor ele- 

 ments of fresh-water limestones. 



The formation has produced a small and not especially characteristic 

 invertebrate fauna, a scant flora of cycads and fossil wood and a very 

 characteristic and varied vertebrate fauna. 



