636 W. T. LEE STRATIGRAPHY OP COAL FIELDS OF NEW MEXICO 



Mancos 



Feet Inches 

 Shale with a few layers and concretions of lime- 

 stone. The upper part, 100 to 200 feet thick, is 

 sandy and yellowish in color, and contains 

 Anomia sp. ; Inoceramus sp. related to /. acutc- 

 plicatus Stanton ; Inoceramus sp. related to 

 /. sagensis Owen; Cardhim sp. ; Gyrodes sp. ; 

 Pyropsis ? sp. ; Volutomorpha novimexicana 

 Herrick and Johnson (U. S. G. S. locality Nos. 

 7171 and 7173) ; but the principal part is dark- 

 colored and contains few fossils, except a veiT 

 large species of Inoceramus. Thin layers of 

 fossiliferous limestone occur near the base and 

 contain Inoceramus lahiatus Schloth ; Inocera- 

 mus fragilis H. and M. ; Prionocyclus icyomin- 



gensis Meek (U. S. G. S. locality No. 7178) 1,405 



Shale with fossiliferous limestone concretions at 

 the top, containing Ostrea luguhris Conrad; 

 Ostrca sp. ; Inoceramus laMatus Schloth. ; Ino- 

 cerainus fragilis H. and M. ; Pecten sp. ; Pinna 

 petrina White; Cardium sp. ; Isocardia sp. ; 

 Anatina sp. ; PJioladomya sp. ; Mactra 1 sp. ; 

 Turritella sp. related to T. whitei Stanton ; 

 Gyrodes sp. ; Volutoderma dalU (Stanton); 

 ActcEon sp. ; Placenticeras sp. ; Prionotropis — 

 two or more species (U. S. G. S. locality No. 



7177) 400 



Limestone containing Inoceramus lahiatus 



Schloth 1 



Shale 175 



Sandstone (Tres Hermanos), quartzose, consist- 

 ing of thin, contorted layers with numerous 

 worm borings and markings of many kinds ; 

 also poorly preserved gastropods and other shells 5 



Shale ( Gastropod zone) 90 



Sandstone (Dakota), white, friable, cross-bedded, 



locally conglomeratic 50 



Shale (Morrison), variegated, and sandstone. . . . 200 



7,970 







The Dakota sandstone is massive, conglomeratic, quartzitic in some 

 places and friable in others, and its thickness changes from 15 to 50 feet 

 or more in relatively short distances. No fossils were found in it, and its 

 reference to the Dakota is based on its similarity in lithologic character 

 and stratigraphic position to the Dakota of neighboring regions. 



The Mancos shale here, as elsewhere in the areas described in this 

 paper, includes several more or less well defined members that can be 



