PREVIOUS INiVESTIGATIONS 581 



Dakota Mancos, and the shale overlying them Lewis. Tlie younger (;oal- 

 bearing rocks, or "Laramie," occur in this region beyond the limits of 

 the La Plata folio, thus making a section of the Cretaceous rocks which 

 has become the standard for southwestern Colorado and northern New 

 Mexico. 



While the work just referred to was in progress in southwestern Colo- 

 rado a series of independent investigations was being carried on by C. L. 

 Herrick, then president of the University of New Mexico, and by others 

 associated with him. They were not in close touch with other investi- 

 gators, and although their work yielded much valuable information the 

 results have not received the attention they deserve. In 1898 Herrick 

 (72) published a preliminary paper, describing some of the Cretaceous 

 rocks near Albuquerque, and two years later a more elaborate report on 

 this region appeared, in which he, in collaboration with Johnson (77), 

 described the stratified rocks extending from the Rio Puerco to the Cer- 

 rillos coal field. Much valuable information was given regarding the 

 Cretaceous rocks below the coal beds, and the coal-bearing rocks were 

 shown on fossil evidence to be of the same age in the Eio Puerco, Hagan, 

 Tijeras, and Cerrillos coal fields and to be older than the Laramie. They 

 were referred to the Fox Hills. This paper was followed in 1903 by one 

 from D. W. Johnson (83), in which the geology of the Cerrillos region 

 is described in detail. The coal measures were referred to the Fox Hills, 

 and a somewhat extensive Pierre fauna was found in the shale below the 

 coal ; also a somewhat extensive Benton fauna was found near the bot- 

 tom of this shale formation, but no fossils characteristic of the Niobrara 

 were obtained. Evidence was found in some places of a commingling of 

 Benton species with some that he regarded as characteristic of the Pierre. 



The work of Herrick and Johnson was not extended to correlate in any 

 way the rocks described by them with those described by Cross and others 

 in southwestern Colorado, and their results, proving that the coal beds of 

 central New Mexico are older than Laramie, seem not to have gained 

 acceptance, for as late as 1907 Campbell (103), in writing of the coal 

 beds of the Cerrillos and Hagan fields, states that "it is highly probable 

 that they are Laramie." 



In 1905 work was begun on the coal fields of New Mexico which has 

 resulted in a series of publications leading up to our present knowl- 

 edge of the coal fields. Schrader (100) traced the Mesaverde and "Lara- 

 mie" formations from southwestern Colorado, where Cross had estab- 

 lished their stratigraphic relations, eastward along the nortbern border 

 of the San Juan Basin and southward to the Gallinas Mountains. Far- 

 ther south the "Laramie" was not identified and the coal-bearing rocks 



