70 GUIDEBOOK OF THE WESTERN UNITED STATES. 
A few miles east of Las Vegas the plateau or bench of the moun- 
tains on which it is situated terminates in a great vertical escarp- 
ment of Dakota sandstone, which overlies the Morrison formation. 
This escarpment overlooks the Canadian and Pecos valleys, which 
lie between the Las Vegas Plateau and the western edge of the 
Staked Plains of Texas. 
At Las Vegas an extra engine is attached to haul the train up the 
heavy grades of the long climb over the south end of the main chain 
of the Rocky Mountains, which lies between Las Vegas and Lamy. 
In order to find suitable grades for crossing this range it was neces- 
sary to deflect the railway line far to the south, for in the country 
west and northwest of Las Vegas the lowest passes through the moun- 
tains are at altitudes greater than 10,000 feet, or more than 2,500 
feet higher than Glorieta Pass, the one utilized. 
On leaving Las Vegas, the train goes southward, at first over a 
rolling plain of the Graneros shale along Gallinas Creek (gahl-yee’nas; 
locally gah-yee’nas). Within 2 miles the base of this shale is reached, 
and the underlying Dakota sandstone appears in railway cuts and in 
the canyon a short distance east of the track. Half a mile beyond is 
a shallow basin of the shale, in which small outliers of the overlying 
Greenhorn limestone rise as hills on both sides of the track. 
Just west of Romero (ro-may’ro) siding the railway turns west into 
a gap through a ‘“‘hogback” ridge that constitutes one of the foothills 
of the mountains. This hogback consists of Dakota 
sandstone and associated rocks steeply upturned on 
ws, the east side of the uplift of the main range of the 
"Rocky Mountains. The ridge is caused by the hard- 
ness of the upturned beds, which resisted to some extent the ele- 
ments that eroded to a lower level the soft overlying shale on the 
east and the red shales on the west. The hogback ridge extends far 
to the north along the foot of the mountains, but toward the south, 
where the dips become gentler, it finally merges into a plateau pre- 
senting steep cliffs to the west and south, which are visible east of the 
railway for several miles. 
Beyond the hogback ridge the railway goes southward up a valley 
of red shale, but in places it bears westward through gaps in several 
small ridges caused by layers of sandstone included in the red shale. 
The manner in which these sandstones give rise to small ridges is an 
instructive illustration of the relation of hard and soft rocks to the 
topography. The hard layers vary in thickness, but all make ridges 
of greater or less prominence. To the west of the railway there rises 
out of the red shale valley a bed of hard sandstone of considerable 
thickness, which constitutes a high ridge extending for many miles 
north and south parallel to the hogback ridge. The relations of these 
rocks are shown in figure 13, a section across the railway in the vicinity 
Romero. 
Elevation 6,287 feet. 
Kansas City 791 mil 
