DESCRIPTIVE details: cabezon 621 



east end of Chacra Mesa, several conifers of the species Ahietites duhius 

 Lesq. were found. 



Two small collections of shells were made from the Mancos shale near 

 Cabezon. One was obtained from the sandy layers at the top of the for- 

 mation in the transitional zone between the Mancos and the basal sand- 

 stone of the Mesaverde. They were found at the point where the wagon 

 road leading northwestward from Cabezon crosses the top of the Mancos 

 shale. They are as follows : 



Fossils from the Top of the Mancos Shale, Northwest of Cahezon 



(United States Geological Survey locality number 7194) 



Ostrea elegantula Newberry ? Mactra sp., related to M. formosa M. 



Anomia sp. & H. 



Pinna sp. Corhula sp. 



Cardiiim sp. Gyrodes sp. 



Cyprimeria sp. Actwon sp. 



Tellina sp. Placenticeras sancarlosense Hyatt . 



Lioplstha undata M. «& H. ? 



The second collection was obtained from the low hill back of the town* 

 of Cabezon at a horizon several hundred feet below the top of the Mancos 

 shale. The rocks containing them are somewhat sandy, and this fact may 

 serve to explain the resemblance of the fauna to that yielded by the sand- 

 stones of the Mesaverde. The fossils are as follows : 



Fossil Shells collected at Cahezon, New Mexico 

 (United States Geological Survey locality number 7195) 



Exogyra sp. Gyrodes sp. 



Anomia sp. Volutomorpha sp. 



Avicula linguiformis E. «& S. Volutoderma ? sp. 



Inoceramus haraMni Morton? Liopeplum sp. 



Mytilus sp. Pyrifusus ? sp. 



Cucullcea sp. Placenticeras sancarlosense Hyatt? 



Crassatellites ? sp. . Btantonoceras pseudocostatum Johnson? 



Cyprimeria sp. Lamna sp. (shark's teeth) 



From a study of fossils collected from the Mancos, in the vicinity of 

 Cabezon, Shimer and Blodgett (109, page 58) arrived at the conclusion 

 that the shale was of Benton age. They found many Benton species asso- 

 ciated with a few which they regarded as belonging to the Pierre fauna. 

 However, the exact horizons of their collections are not known to the 

 present writer, and it is possible that they may be somewhat lower than 

 the horizons at which the fossils named above were found. In the light 

 of the more recent investigations, Doctor Stanton is of the opinion that 



