PENNSYLVANIAN FORMATIONS IN THE RIO GRANDE 815 
makes it the equivalent of a series to which the name Ladronesian is 
applied. No evidence in support of this separation is given, and 
Herrick specifically states that none exists. For the remaining 
part of the Magdalena division Keyes uses the term Manzanan. 
Even a cursory reading of Herrick’s description is sufficient to show 
that these are not the beds for which the name Manzano was origi- 
nally proposed. For subdivisions of the rocks included under his 
term Manzanan, Keyes uses, in addition to Herrick’s terms Sandia 
beds and Coyote sandstone, the name Montosa for the limestone 
below the Coyote sandstone, and Mosca for that above. No evidence 
is given that will warrant the establishment of these formation names. 
Our own observations lead us to conclude the Coyote sandstone to 
be of local development and the subdivision of the Madera formation 
to be unsupported by the evidence thus far available. 
Overlying his so-called Manzanan, the same author? notes a 
limestone formation which he calls Maderan. Evidently he regards 
this as the same formation which in an earlier paper he says is, in the 
Sandia Mountains, called the Madera limestone, and adds that it 
forms by far the most important portion of the Carboniferous in 
all the mountain ranges mentioned. From Herrick’s description 
of the geology of the Sandia Mountains, which is corroborated by 
the studies of W. T. Lee,? of the U. S. Geological Survey, it is clear 
that the great limestone formation of the Sandias is the limestone which 
constitutes the upper half of our Magdalena division and comprises 
the formations to which in the same table3 Keyes gives the names 
Montosa and Mosca, with the included Coyote sandstone. The 
discrepancies in this case are apparently due to confounding the 
Madera limestone in some places with the limestones at the top of 
the Manzano group. Inasmuch as the name Madera very appro- 
priately applies to the limestone overlying the Sandia beds in the 
Sandia Mountains, it may well be retained for the upper formation 
of the Magdalena division. 
In the following table is presented, in convenient form for com- 
parison, the classifications of the Pennsylvanian rocks in the Rio 
Grande region by the different authors mentioned. 
1 “Water-Supply Paper, No. 123,” U. S. Geol. Survey Report, p. 22, 1905. 
2 Personal communication. 3 Jour. Geol., Vol. XIV, p. 154, 1906. 
