NOTES ON THE PENNSYLVANIAN FORMATIONS IN 
THE RIO GRANDE VALLEY, NEW MEXICO: 
C. H. GORDON 
Knoxville, Tenn. 
Introduction. 
General Relations of the Pennsylvanian Rocks in the Rio Grande Valley. 
The Magdalena Group. 
General Description. 
The Sandia Beds. 
The Madera Limestone. 
The Manzano Group. 
Nomenclature. 
INTRODUCTION 
A number of papers have appeared in recent years concerning 
the Carboniferous formations in the Rio Grande Valley. As the 
observations therein recorded were almost wholly of a reconnaissance 
nature, it is not to be wondered at that more or less divergence is 
manifest in the views of the different writers concerning the stratig- 
raphy of the region. This paper is based on observations made 
during a year’s residence at Socorro, together with several months’ 
field-work in connection with the investigation of the mines and 
mining districts of New Mexico under the direction of Mr. Walde- 
mar Lindgren of the U. S. Geological Survey. The results of that 
investigation are to appear in a forthcoming bulletin of the Survey. 
In the present paper it is the chief purpose of the author to 
present a brief description of the rocks in the Rio Grande Valley 
which represent the lower part of the “Coal Measures” of adjoining 
regions, and to discuss their stratigraphical relations and the nomen- 
clature connected with them. For these beds in the Survey paper 
above mentioned the name Magdalena has been adopted as a group 
term. 
t Published by permission of the Director, U. S. Geological Survey. 
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