SAN FRANCISCO MOUNT—-TABLE-LANDS AND PLAINS. 7 
this mountain appears to rise upon a great swell of the surface which has an extension towards 
the south, and yet is without the ridge-like character of a mountain chain. The line of the 
barometric profile passes along the southern base of the volcano and over the broad streams 
and fields of lava which have coursed down its sides and from its numerous secendary cones, 
until it appears as if the great mountain itself was formed by such accumulations. These 
accumulations of lava have doubtless modified the relief of the former surface to such an extent 
that it becomes visible in the profile, but the great swell or rise which is shown, is unquestion- 
ably over an extended uplift of the region, which, though possibly produced by the action of 
the volcano, is nevertheless independent of the great cone, which rises to an elevation of 4,673 
feet above the surrounding region, and consequently to about 13,000 feet above the sea. With 
the exception of the Santa Fé mountains this is the highest summit in the vicinity of the 35th 
parallel. This mountain has a wide base, and does not consist of one single cone, but is flanked 
by a number of smaller craters or openings towards the east and south of the summit. Subordi- 
nate elevations, called Mount Kendrick and Mount Sitgreaves, adjoin it on the northwest. 
TABLE-LANDS, PLAINS, MOUNTAIN SLOPES, AND VALLEYS. 
Having considered the dominant mountain chains which cross the line of survey, a glance 
must be taken of the valleys and plains by which they are separated and above which they rise. 
The approach to the Santa Fé mountains from the Mississippi is by a gentle ascent from an 
elevation of 460 feet at Fort Smith to near 6,500 at the base of the mountains. To reach this 
elevation a horizontal distance of about eight hundred miles is traversed; and the rate of ascent 
being nearly uniform, or but slightly increasing with the altitude, the slope becomes imperceptible 
to the traveller, and the country over which he passes has the aspect of a wide plain. As the 
elevation is increased and the streams have worn deep valleys, the slope becomes a vast table- 
land. This is the character of the slope traversed by the expedition, and its uniformity is shown 
by the barometric profile taken along the valley of the Canadian and Washita rivers. If, 
however, we pass towards the mountains a short distance further south, or at & point where 
the plain has not been furrowed by streams, we shall probably find that the ascent becomes 
step-like and that a series of bluff ascents are reached, each one succeeded by a level area 
higher than the last. These sudden ascents, when compared with the whole elevation, are so 
slight that they become almost imperceptible when represented on a profile drawn to a scale 
equal for heights and distances. The most interesting modification to which this broad slope 
or table-land of the mountains has been subjected, is produced by the erosion of the streams, 
which have eaten out deep valleys, and have, as it were, ‘‘ blocked out” vast areas of the 
surface. "This slope, even along the Canadian, is characterized by the bluff-like margin of its 
highest levels, which mark the limits of the desert-plain known as El Llano Estacado or Staked 
Plain. "These borders are not one continuous bluff, but are deeply indented and bordered by 
outlying hills, remnants of the plain from which they have been severed by the action of 
drainage water, and which are rapidly wearing away, so that the table-like summit will be 
reduced to a mere point, and the elevation become a conical hill. 
The Llano has a wide extent in the latitude of the survey. It reaches from the Sandia mount- 
ains east about three hundred miles, being partly within the State of Texas, and terminating near 
longitude 101° 30. It extends southerly towards the great bend of the Rio Grande, and was 
crossed by Captain Pope, in his survey along the 32d parallel. It also extends north of the 
Canadian, but its limits in this direction have not yet been explored. The line of the survey 
crosses a narrow part or projection of this vast plain between Camps 45 and 46; but the course 
of the exploration being in the valley of the stream, the uniform elevation of the surface of the 
Llano does not appear in the profile. For the purpose of giving a more striking view of the 
configuration of the plain, I have constructed the geological profile as if the line of observation 
had extended over its widest part. The elevation of the portion of the Llano crossed over was 
