70 EXPLORATION OF THE CANONS OF THE COLORADO. 
camp. It is no easy task to find my way down the wall in the darkness, 
and I clamber about until it is nearly midnight, before I arrive. 
July 30. We make good progress to day, as the water, though smooth, 
is swift. Sometimes, the canon walls are vertical to the top; sometimes, they 
are vertical below, and have a mound covered slope above ; in other places, 
the slope, with its mounds, comes down to the water's edge. 
Still proceeding on our way, we find the orange sandstone is cut in two 
by a group of firm, calcareous strata, and the lower bed is underlaid by soft 
gypsiferous shales. Sometimes, the upper homogeneous bed is a smooth, 
vertical wall, but usually it is carved with mounds, with gently meandering 
valley lines. The lower bed, yielding to gravity, as the softer shales below 
work out into the river, breaks into angular surfaces, often having a columnar 
appearance. One could almost imagine that the walls had been carved with 
a purpose, to represent giant architectural forms. 
In the deep recesses of the walls, we find springs, with mosses and ferns 
on the moistened sandstone. 
July 31. We have a cool, pleasant ride to day, through this part of the 
canon. The walls are steadily increasing in altitude, the curves are gentle, 
and often the river sweeps by an arc of vertical wall, smooth and unbroken, 
and then by a curve that is variegated by royal arches, mossy alcoves, deep, 
beautiful glens, and painted grottos. 
Soon after dinner, we discover the mouth of the San Juan, where we 
camp. The remainder of the afternoon is given to hunting some way by 
which we can climb out of the canon ; but it ends in failure. 
August 1. We drop down two miles this morning, and go into camp 
again. There is a low, willow covered strip of land along the walls on the 
east. Across this we walk, to explore an alcove which we see from the river. 
On entering, we find a little grove of box-elder and cottonwood trees ; and, 
turning to the right, we find ourselves in a vast chamber, carved out of the 
rock. At the upper end there is a clear, deep pool of water, bordered with 
verdure. Standing by the side of this, we can see the grove at the en 
trance. The chamber is more than two hundred feet high, five hundred feet 
long, and two hundred feet wide. Through the ceiling, and on through the 
rocks for a thousand feet above, there is a narrow, winding skylight ; and 
