THE DISTRIBUTION OP THE TRIAS. 
39 
proper place. But there are some other exposures which mei’it particular 
notice. They are found upon the summit of the Paria Plateau, a mass of 
Triassic and Permian strata of great extent, which has been spared in the 
general denudation. These Jurassic remnants are far away from the prin- 
cipal body. A distance of nearly 35 miles separates the remotest one 
from the Jurassic terrace on the north, and about half that interval lies 
between them and the same formation at the foot of the Kaiparowits. 
These outliers, situated so far out in the heart of the Grand Canon district 
and within a few miles of the Colorado, are noteworthy as fragments of 
evidence indicating the former extension of the Jurassic over the entire 
surface of the denuded platform drained by the Grand and Marble Canons. 
The extension of the Jura south of the Colorado and its exposure in ' 
the line of the Echo Cliffs has been traced for nearly 60 miles. Its 
mode of resolution there is at present unknown, and must be ascertained 
by future exploration. Enough has been learned, however, to establish the 
fact quite positively that its general relations to the Grand Canon district 
are in all essential respects the same as those of the Cretaceous above it 
and of the Trias beneath it. Its broken edges wall the district on two sides, 
the north and east, and its littoral belt along the Mesozoic shore line of the 
Great Basin goes far towards establishing its former existence along a great 
part of the third or western side. Finally, the occurrence of advanced 
outliers upon the Paria Plateau extend it far out into the interior spaces of 
the Grand Canon district. 
THE TRIAS. 
The splendor of the terraces culminates in the Trias. It is separated 
from the Jurassic at the provisionally adopted horizon by a conspicuoiis 
change in the aspect of its component strata and in the grouping and habit 
of the whole series. Sometimes, however, the dividing horizon is obscured 
by a transition from one to the other through a gradually changing mass of 
sandstone; but more frequently the passage is abrupt. The Jurassic sand- 
stone is without a likeness in any other formation, and the sandstones of the 
