IOWA ACADEMY OF SCIENCES. 
171 
ous rocks of New Mexico are the formations in which 
occur extensive lead deposits just as they are in the 
Mississippi Valley. 
In New Mexico there are no coal-bearing terranes of 
Carboniferous age. Extensive deposits of bituminous coal, 
anthracite, and lignite occur in the New^ Mexican Cretace- 
ous formations which are upwards of 7,000 feet in thick- 
ness. In this connection it may be mentioned that the 
coal deposits of New Mexico are more extensive than those 
of the whole of the Mississippi Valley. 
Extensive beds carrying the Lower Burlington fauna 
also have been found recently in the San Andreas range 
and in the Sierra Oscura in east-central New Mexico, 
seventy-hve miles east of Lake Valley. 
From these statements it may be inferred that the 
Lower Burlington faunas will be found very widely dis- 
tributed in the southwest — probably over all the south- 
western half of New Mexico, extending on into Arizona and 
northern Mexico. 
