J. J. Stevenson— Geology of Galisteo Creek. 471 
Art. LVITI.—Noies on the Geology of Galisteo Creek, New Mex- 
ico; by JoHn J. STEVENSON, Professor of Geology in the 
University of the City of New York. 
GALISTEO CREEK rises near the southern end of the Santa 
Fe mountains and flows southward for nearly fifteen miles to 
Galisteo; where, being increased by the Arroyo San Cristobal, 
coming from the east, it turns westward and flows in that direc- 
tion to the Rio Grande. Its area is divided by a narrow dike, 
which forms a distinct ridge and separates the portion drained 
by the creek in its southward flow, from that drained by the 
Arroyo San Cristobal and the creek in its westward flow. 
These divisions may be distinguished as the upper and the 
lower area of the Galisteo. The region is not wholly unknown 
to geologists, for it has been visited by Dr. Newberry, Dr. 
Hayden and Professor Cope, whose views respecting the age of 
the coal beds and of the peculiar Galisteo sandstone are not in 
accord, The details of my observations there will be given in 
my report to Captain Wheeler; here, by consent of the Chief 
of the Engineer corps, U. S. A., a brief résumé of the results 
will be given, in so far as they bear upon the matters in dispute. 
The shales of the Fort Pierre group (No. 4 of Mr. Meek’s 
general section) are shown at barely sixteen miles below Gal- 
isteo dipping gently eastward in mesas on both sides of the 
creek. They have all the characteristic features of that group 
and yield its peculiar fossils at many localities. The Laramie 
group rests on them, and its western outcrop is reached on the 
South side of the creek at somewhat less than sixteen miles 
below Galisteo. There the rocks dip toward the east-northeast 
and at a low angle; this is the northern termination of an ex- 
tensive area of Laramie, reaching southward for many miles 
and surrounding the Placer and Sandia mountains. The eastern 
Outerop of the Laramie beds passes rudely north and south 
through Galisteo, and there the dip is westward. The width of 
the area from east to west along the creek is not far from fif- 
teen miles. 
A detailed section of 440 feet, taken on the western outcrop, 
bears no resemblance in detail to sections from the same horizon 
in the Trinidad coal field, and correlation of the beds in the two 
fields is not possible. The coal beds in the Galisteo area are 
thin and variable, and little of economic interest exists aside 
from the anthracite beds, which contain coal altered by the in- 
fluence of a gigantic dike passing between the Placer mountains 
and Galisteo creek. But there is much material of scientific 
interest, for the Laramie beds show an unexpected intimacy 
with the underlying Fort Pierre. 
