RED BEDS OF RIO GRANDE REGION 57 
found to differ in composition from the older beds and to lie strati- 
graphically above fossiliferous limestones and shales of Upper Cre- 
taceous age. At the northern end of Caballos mountains, two miles 
south of Elephant Butte, the Upper Carboniferous formations, 
including the older Red beds, together with their underlying and 
overlying limestones, occur overlain by fossiliferous strata of the 
Benton formation, which in turn is followed by an extensive series 
of Cretaceous sandstones, containing beds of coal at its base, 
and great quantities of fossil wood at higher horizons. ‘The leaves 
and tree trunks of both monocotyledonous and dicotyledonous varieties 
are numerous. Palm wood is particularly abundant. 
The red sandstones and shales constitute the uppermost exposed 
member of the coal-bearing sandstones and, in addition to the fossil 
plants, contain Dinosaur bones. No excavations were made in order 
to secure satisfactory material for specific determination, but Mr. 
J. W. Gidley, of the National Museum, who examined the collections, 
states that the Dinosaurs belong to the genus Tviceratops, clearly 
indicating that these red beds are of late Cretaceous age. 
A similar series of red sandstones and conglomerates occurs at 
the northern end of the region, and was observed above the coal- 
bearing sandstones near Cerillos, and again near the Hagan coal- 
fields, a few miles south of Cerillos. In both of these localities the 
red sediments occur at the top of the Upper Cretaceous section and 
contain great quantities of petrified wood, but are otherwise unfos- 
silferous, so far as known. 
The conglomerates of this formation are made up of pebbles, of 
various igneous and metamorphic rocks, together with limestones 
containing Carboniferous fossils, and red sandstones similar to those 
of the older or Carboniferous Red beds. Many of the pebbles are 
only slightly rounded and were apparently transported but short 
distances. The upper part of the formation, throughout an exposed 
thickness of about 200 feet near Hagan, is a conglomerate composed 
mainly of fragments of andesite. 
This formation was originally described by Hayden? as the Galisteo 
sands. On account of the strong resemblance in physical character, 
t F. H. Hayden, U. S. Geological Survey of the Territories for 1867, 1868, and 
1869, reprint 1873, p. 166. 
