172 ANNALS NEW YORK ACADEMY OF SCIENCES 



spond, bed for bed, or even generally, with the beds in another section. 

 It is also reasonable to suppose that some whole sections in certain areas 

 are slightly younger or older than other whole sections in other areas. 

 It appears, then, that the Morrison commenced as a continental deposit 

 in the western areas of its occurrence in early Coinanchean time (or 

 possibly latest Jurassic), and that it spread outward as it was built up, 

 the uppermost and easternmost beds being laid doion in Comanchean 

 time. The upper beds are generally fine-grained as compared with the 

 lower ones. This suggests that the mountain areas to the west were being 

 worn down and that the streams had only sufficient gradient, on the 

 average, to carry fine material. 



The exact relation of the Morrison to the marine Comanchean is not 

 definitely known, except that Washita beds are known, in one or two 

 cases, to overlie the Morrison. If the above interpretation of the Morri- 

 son be anything like the truth, it seems probable that the Morrison merged 

 into the marine deposits in the southeastern areas, such as Texas, and 

 that the Morrison in its southeastern and eastern areas consisted of true 

 delta deposits. 



BIBLIOGEAPHY i° 



1821. 1. James, E. P. : "Remarks on the sandstone and floetz trap formation 

 of the Valley of the Mississippi." Amer. Philos. Soc, Trans., vol. ii, pp. 

 191-215, 1821 (read Aug. 17, 1821). [General description of the hog-backs, 

 etc.] 



1823. 1. Long, Stephen H. : Account of an expedition from Pittsburgh to 

 the Rocky Mountains, performed in the years 1819-20 ; compiled by Edward 

 James. Yol. i, 503 pp. ; vol. ii, 442 pp. ; atlas of 11 sheets, 1823. [Descrip- 

 tions of sediments at the east base of the Rocky Mountains.] 



1859. 1. Meek, F. B., and Hayden, F. V.: [Some remarks on the geology of 

 the Black Hills and portions of the surrounding country.] Phila. Acad. 

 Sci., Proc, vol. X, pp. 41-49, map, 1859. [Section and description of beds 

 around the Black Hills.] 



1861. 1. Newberry, J. S. : "Geological report." Colorado Exploring Expedi- 

 tion, Lieut. J. C. Ives in charge, 154 pp., 28 figs., 4 plates, 1861. [Sections 

 and descriptions of the beds, some of vp^hich probably include Morrison.] 



" All important papers are listed, though the bibliography is not absolutely complete, 

 especially in regard to very early papers. Works on the principles involved in the dis- 

 cussions in the present paper are included, as well as works dealing directly with the 

 Morrison formation. The bibliography of the paleontology of the Morrison is not in- 

 cluded, as it would add hundreds of titles which are of no value from the point of view 

 of this work, being anatomical in nature. The original references to the various genera 

 and species are given in the section on paleontology, with a few of the more important 

 subsequent references. 



