660 WHITMAN CROSS 
in it and it has not been described in detail as to the character, size, 
and abundance of the pebbles. But from the mouth of Paria River 
southeast, below the Echo Cliffs, which are mainly formed of the 
Vermilion Cliff sandstone, the Shinarump conglomerate has unfor- 
tunately not been absolutely traced, so that its relation to the vertebrate- 
bearing beds found by Ward in the Little Colorado Valley is uncertain. 
The vertebrate fauna obtained by Ward and Brown (39, 40) from 
several localities near the Little Colorado from the midst of the strata, 
rich in fossil wood, is clearly the same as, or similar to, that so widely 
known in the Dolores formation, the most common form being the 
crocodile of which the type was found by Gane in the Dolores at Clay 
Hill. Ward does not identify the Shinarump conglomerate as a 
single marked bed, but applied the term to 800 feet of strata entirely 
below the vertebrate-bearing horizon (40). Dutton, on the other 
hand, has thought to recognize the Shinarump conglomerate in 
typical development as far east as the Zuni Plateau in New 
Mexico (11). 
At the present time, it seems to me not improbable that the horizon 
of the original Shinarump conglomerate of the Shinarump Cliffs is 
near, if not equivalent to, the vertebrate-bearing strata of the Little 
Colorado Valley, being there perhaps less conspicuously conglom- 
eratic than in the type locality. The “conglomerate” is usually 
described by Dutton and others as really a coarse sandstone with 
pebbles irregularly scattered through it. Dutton ascribes a fluviatile 
origin to it, and such is also clearly the mode of formation of the 
Dolores conglomerates, which vary greatly in character in different 
places. It is surely not unlikely that beds of this character, but of 
different horizon, have been mistaken for the same by reconnaissance 
observers at widely separated points. This might be suspected from 
the character of the so-called conglomerate alone, and is rendered 
quite plausible by Ward, who found sandstones containing some 
pebbles variably developed in different sections through some 800 
feet of strata (40). 
The occurrence of a vertebrate fauna of upper Triassic age over 
a wide expanse of country, in Arizona, Utah, Wyoming, Colorado, 
New Mexico, and probably also in Texas, seems the most definite fact 
from which to start in studying the problem of the western Trias. 
