[ANNAis N. Y. Acad, Sci., Vol. XXVII, pp. 39-191, PI. VI. 12 June, 1916] 



STUDY OF THE MOEEISON FOKMAT^^JnianS/>-. 



/c^ ''o 



By Charles Craig Mook /^ a) ir o o ioir 



iv^ AUb 2o1916 '^ 



(Presented before the Academy, S May\19^) ■ 



CONTENTS ^""-**.™L««.*'^^ 



Page 



Introduction 40 



Preliminary remarks 40 



Definition of formation 41 



Physiographic occurrence and distribution of the Morrison formation. 42 



Purpose and scope of present work 43 



Stratigraphy 43 



Morrison formation in eastern Colorado and New Mexico 43 



General 43 



Northern Colorado 45 



Morrison 47 



CaSon City area 48 



Canyons of southeastern Colorado 56 



Eastern New Mexico and Oklahoma 61 



Morrison formation in western Colorado and eastern Utah 66 



Grand River area 71 



Northeastern Utah and northwestern Colorado 78 



Morrison formation in Montana and Wyoming (except the Black Hills 



area) 80 



Central and southern Montana 80 



Bighorn Mountains 82 



Shoshone River region '. . 86 



Central and southern Wyoming 87 



Morrison formation in the Black Hills area 99 



Atlantic coast representative of the Morrison 109 



Arundel formation of Maryland 109 



Summary of stratigraphie relations and characters of the Morrison 



formation 110 



Distribution 110 



Rela tion to underlying rocks 110 



Relation to overlying beds ' 112 



Thickness ' 113 



Lithologic characters , 115 



Variable character of sections ' . . 115 



Structure and petrography 115 



Structural features of the Morrison formation 115 



Petrographic characters of the Morrison formation 119 



^ Manuscript received by the Editor 18 May, 1915. 



(39) 



