5 Pr he ee: et he eee oe 
THE SANTA FE ROUTE. 91 
Mount Taylor, 11,389 feet high. It will be seen that the mesa or high 
plain of Santa Fe marl extends far to the north and south, partly 
filling a broad basin between the mountains. Originally its surface 
was a continuous plain, but the Rio Grande has cut a wide valley 
_ for itself 200 feet or more deep through the center of the plain, and 
now the river flows along the bottom of this valley, with a mesa or 
plateau of the ‘‘marls” forming cliffs or slopes on each side. 
After crossing the low divide on the plateau beyond Sandia sid- 
ing the train descends by a tortuous route to the valley of the Rio 
Puerco (pwair’co, Spanish for dirty). On the way it passes through 
many cuts in the Santa Fe marl that exhibit the characteristics of 
the deposits, which are mostly sands and loams, in some places 
consolidated into loose sandstones. 
The Rio Puerco is a long stream draining the mesa country to the 
northwest and emptying into the Rio Grande some distance southeast 
of the crossing. Its valley is excavated mostly in soft beds of the 
Santa Fe marl and underlying shales (late Cretaceous). To the west 
is the Mesa Lucera (loo-say’ra), a plateau capped by a thick sheet of 
lava (basalt) lying on sandstones and shales. These strata dip 
steeply eastward in a low line of foothills extending along the east 
side of the mesa, but they are nearly level under the lava cap. 
A short distance south of Rio Puerco station there are several 
small knobs of volcanic rock rising above the wide valley bottom. 
of Rio Puerco siding the old main line is paral- 
Rio Puerco. leled for a few miles by a new track diverging to the 
Elevation 5,049 feet. Jeft, for the westbound traffic and rejoining the old 
ny %3 mS: Fine a short distance beyond South Garcia (gar-see’ah) 
siding. From Rio Puerco to the Continental Divide, a distance of 
nearly 100 miles, the railroad ascends the valley of the San Jose 
(ho-say’), which empties into the Rio Puerco at Rio Puerco station. 
age, capped on some of the plateaus and | far to the north of the railway in New 
mesas by thick sheets of lava. At many | Mexico, Arizona, and Utah, and for some 
places high cones or necks of older vol- | distance to the south through central New 
canic rocks rise above the platforms, and | Mexico. It is a region in which the 
widely scattered cinder cones mark the | constituting the earth’s crust have been 
Mountain country on the east and the | bodily up or down on one side in rela- 
region of deserts and long rugged ridges on | tion to those on the other side. These 
. peculiar structural eon re sa to’a 
This section of the country is one of | special kind of stresses in earth’s 
great interest to the student of geology, | crust, are here localized in a zone od rela- 
‘illustrations of geologic features meee a oe of the strata by folds 
than the adjoining provinces. It extends | and faul 
