2 
MESOZOIC FORMATIONS. 
the road, rising less rapidly, passes over lower horizons, finally reaching a bed 
of hard, light, and rather coarse sandstone. At this point, the route turns to 
the northward, leaving the river, and climbs a low, long hill, whose surface is 
sandstone without soil. A few miles beyond, the summit is reached, and is 
found to present a sage-brush plain, many miles in extent, which is bor¬ 
dered by hills of remarkable beauty. To the south, the cation of the Chama, 
with the Abiquiu Peak and other mountains beyond it, bound the plain 
while, to the east and north, the brilliantly colored strata above described 
form a perpendicular wall of about five hundred feet elevation. The upper 
third or more of this precipice is of a lemon-yellow, the remaining and 
lower portion of a sub-vermilion-red, forming a beautiful combination. The 
rock is fissured by ravines, and the intervening portions rise as huge but¬ 
tresses of varied proportions, sometimes especially prominent near the sum¬ 
mits, often forming regular bastions. Near the base, certain bluish strata 
form naked mounds and hills of bad-land character; but I failed to discover 
any fossils on them. The southern face of this wall presents a tremendous 
fissure, the “puerta” of the Cafion Cangilon. Our route laid through this 
defile for many miles, and we thus obtained an excellent section of the 
higher level of the region. 
The yellow beds above mentioned were described at the close of Chap¬ 
ter III (of Ann. Kept.) as being overlaid with a shale, and this again by an 
arenaceous conglomerate. These formations increase in thickness north¬ 
ward, and near the mouth of the Canon Cangilon a bed of fractured gypsum 
appears above the shale ; the former soon becoming 25 feet in thickness, the 
latter only 3 feet. Along the sides of the southern part of the cation, the 
gypsum forms a snow-white bed of 50 feet in thickness, overlying the walls 
of yellow and red, and its borders are cut into fissures by the atmospheric 
erosion. From these points, the stain produced by the dissolved gypsum 
forms stripes or fan-shaped shades of a beautiful mauve J;int, which gives 
these rocky walls the appearance of a changeable silk; the mauve repre¬ 
senting the shadows, and the red and yellow the lights. Altogether, the 
picturesque forms, brilliant hues, and regular cleavage of the precipices 
which for miles bound this cafion, form a scene of unusual beauty. The 
beds soon present a northwest dip. The gypsum descends from its elevated 
