THE CHASM AT THE FOOT OF THE TORO WE AP. 
89 
ing is notably weakened by weathering. Still lower are red-brown sand- 
stones again, having a dark and strong shade and lying in very massive 
beds. The strata forming the walls of the outer chasm from the summit to 
the plain below are designated the Aubrey group, and this is again subdi- 
vided at the base of the cross-bedded plinth into upper and lower Aubrey 
groups. The two subdivisions are believed to be the equivalents, in age, 
of the coal measures of Pennsylvania and England. The strata disclosed 
in the inner gorge correspond in age to the lower Carboniferous of those 
countries, and are here termed the Red Wall group. Some uncertainty 
exists regarding the beds which lie at the base of the conformable series 
deep down in the chasm, but they are regarded at present as being just 
what they seem and just what they would naturally be inferred to be — a 
part of the Carboniferous system. Of the strata at the bottom of the canon, 
we shall have more to say hereafter. They are regarded at present as being 
of lower Silurian or Primordial age. 
The observer who, unfamiliar with plateau scenery, stands for the first 
time upon the brink of the inner gorge, is almost sure to view his surround- 
ings with commingled feelings of disappointment and perplexity. The 
fame of the chasm of the Colorado is great ; but so indefinite and meager 
have been the descriptions of it that the imagination is left to its own de- 
vices in framing a mental conception of it And such subjective pictures 
are of course wide of the truth. When he first visits it the preconceived 
notion is at once dissipated and the mind is slow to receive a new one. The 
creations of his own fancy no doubt are clothed with a vague grandeur and 
beauty, but not with the grandeur and beauty of Nature. When the reality 
is before him the impression bears some analogy to that produced upon the 
visitor who for the first time enters St. Peter’s Church at Rome. He expected 
to be profoundly awe-struck by the unexampled dimensions, and to feel ex- 
alted by the beauty of its projDortions and decoration. He forgets that the 
human mind itself is of small capacity and receives its impressions slowly, 
by labored processes of comparison. So, too, at the brink of the chasm, 
there comes at first a feeling of disappointment ; it does not seem so grand 
as we expected. At length we strive to make comparisons. The river is 
clearly defined below, but it looks aboixt large enough to turn a village 
