BANKS OF GALISTEO CREEK. 99 
From a locality north of Galisteo I have specimens of greenish brown calcareous shale, con- 
taining many fragments of Jnoceramus and obscure impressions of Ammonites. These fossils 
are too fragmentary for specific determination, but a precisely similar rock, containing like or- 
ganic fragments, is exposed on the banks of the Ocaté and Canadian. Its place in the series 
is at the base of the Upper Cretaceous group, immediately over the coarse yellow or reddish 
sandstones of the lower division of that formation. It is probable that the strata containing 
Cretaceous fossils at Poblozon are of the same age with these. P 
On the north side of Galisteo creek we found the sedimentary rocks just enumerated cut 
through in many places by trap dikes, having various directions. These dikes, composed of 
more resistant material than the strata once enclosing them, have been left by the erosion of | 
the softer rocks in walls of most artificial appearance. The trap is columnar, the columns lying 
horizontally as usual, having been formed with their axes at right angles to the cooling surfaces, 
Some of these walls were noticed which extend for long distances with a nearly uniform height 
of four or five feet, closely resembling old field walls. Others are less extensive but higher, 
and occasionally pierced with holes, resemble the walls of ruined buildings. The ends of the 
columns are distinctly visible on the surface of these dikes, imitating so perfectly the appear- 
ance of masonry that it is not surprising, in the country once exclusively occupied by the 
Pueblo Indians, they should have been generally regarded by the unlearned as the ruins of 
human habitations and enclosures. 
The valley of Galisteo creek is bounded on the north by high, and in many places perpen- 
dicular bluffs of trap, the cut edges of a plateau of that material which occupies a large space 
in this vicinity. From this mesa rise the volcanic cones of the ‘‘ Cerrillos,’’ as I have sup- 
posed, marking the place of origin of the lava floods which once deluged the surrounding 
country. 
The Cerrillos furnished a great part, if not all, the chalchwitl, so much worn for ornament, 
and so highly prized by the ancient Mexicans. This mineral is a variety of turquoise, and is 
found in veins running through a light-colored trachyte.* The ancient excavations made in 
search of it are now distinctly visible, and seem to have been carried to the depth of two hun- 
dred feet or more. Several of the Indian tribes of New Mexico—Navajos, Mojaves, &c.— 
still hold this gem in the highest esteem. The most valued possession of Cairook, a Mojave 
chief, was a wedge-shaped piece of chalchuitl, suspended from his nose. At Romero’s we 
reached the edge of the trap mesa. Thence to Santa Fé the only rock visible in place is a 
soft red calcareous sandstone of the Marl series, which forms low hills, generally covered by 
drift from the adjacent mountains. 
The Santa Fé mountains are a part of the great Rocky mountain system, and constitute its 
only important representatives met with on our route. They form a series of high and pic- 
turesque chains, connecting on the north with the Raton mountains, the Spanish peaks, and: 
the lofty summits around the ‘‘Parks;’’ while on the south they are represented by the Sandia, 
Organ, Hueco, and Guadalupe ranges, east of the Rio Grande. The general bearing of the 
Santa Fé mountains is about north northwest and south southeast, but some of the ranges com- 
posing this compound system depart widely from that trend. With their connexions, they 
include many peaks and sierras covered with perpetual snow, which formed prominent features 
in the scenery of more than two hundred miles of our route. ; 
From the fact that this group of ranges is not continuous southward, they permit the passage 
through them of the drainage of the basin of the upper Rio Grande, and therefore are not the 
divide between the waters of the Atlantic and Pacific in New Mexico, though they are so in 
Utah. The line of elevation which really forms the divide is, however, in other respects, 
a much less important topographical feature than that under consideration; for, as has been 
©To Mr. J. Mercure, of Santa Fé, I am indebted for fine specimens of this, as of many other minerals and ores, found in 
this part of New Mexico. : cee : ae 
