68 
THE GRAND GANON DISTRICT. 
striking cliaracteristics of the strata of the Plateau Country is the remark- 
able constancy of the character of each formation over vast expanses of 
country, and the extreme slowness with which their thickness varies from 
point to point. 
It still remains to inquii’e whether we are to assume this extension for 
the entire Mesozoic sj^stem, together with the Permian below and the Eocene 
above, or if it applies only to the older of these formations; for instance, 
the Permian and Trias. It may be replied that while the presumption is 
very strong in favor of the whole the weight of evidence varies with the 
different formations. In the case of the Permian it is conclusive. Innu- 
merable remnants of this formation are scattered over the Carboniferous 
platform, and the eye and mind carry the connection easily from one rem- 
nant to the other. In the Trias the outlying remnants are very few, yet 
these few are situated in such a manner that they leave no reasonable 
doubt; and the Trias carries the Jura with it. The two formations are so 
nearly co-extensive, and are so intimately associated that the very small 
difference in the distribution of their masses now remaining will not appre- 
ciably affect the conclusions to be drawn. So, too, of the Cretaceous. 
This series is wanting from some Triassic ai-eas, but we should naturally 
expect the higher formation to be more eroded. No geologist would hesi- 
tate to restore it to those areas where the Trias is found, and yet when this 
is done it is impossible to see how the question of its further extension 
would differ from that of the Trias. 
The Eocene presents undeniably a somewhat greater difficulty; 
greater, however, in degree and not different in kind. This formation is 
found only on the northern side of the district and in the littoral belt. It 
is unknown in the great mesas which are bounded westward by the Echo 
Cliffs. We find it again only in New Mexico. But the wonder is, not that 
the Eocene is wanting from such vast areas, if it was deposited over them, 
but rather that so much of it remains. Still the main argument which has 
been applied to the other formations holds good when applied to this one. 
We cannot find any reason for terminating its former extension short of 
the ancient shore-line in Arizona; but the additional argument from out- 
lying remnants is no doubt weaker. It seems best, therefore, to regard 
