654 WHITMAN CROSS 
glomerate, and through his kindness I am able to give the report 
made upon these fossils by Mr. T. W. Stanton, as follows: 
The collection of invertebrates collected by Mr. L. M. Prindle contains many 
good casts and imprints of Unio, apparently belonging to three or more species. 
These are comparable and possibly identical with Unio cristonensis Meek, U. 
dockumensis Simpson, and U. dumblet Simpson, all of which come from sup- 
posed Triassic beds. Unio cristonensis was described with two other species 
from fragmentary specimens obtained by Cope on Callinas Creek, New Mexico. 
The Moab specimens are much larger than the types but they agree in outline 
and general proportions. ‘The other two species above mentioned were obtained 
by the Texas Geological Survey in the Dockum beds of northwest Texas. These 
beds have yielded four species of Unio, which, with the three species from about 
the same horizon in New Mexico, are the oldest known representatives of the 
genus. ‘The species in the Moab collection seem to belong to the same Unio 
fauna. 
That in this vicinity a stratigraphic break of much importance 
occurs just below the “‘saurian conglomerate,” as it has been called 
in the San Juan region, is evident on Grand River and at other places. 
On the west side of Grand River opposite Moab the bone-bearing 
conglomerate is separated from fossiliferous Pennsylvanian beds by 
only about 50 feet of shaly sandstone, and it is possible that these 
beds also belong to the Pennsylvanian series. Details of the section 
at this point are given on p. 669. 
Near Moab, on the northeast side of Spanish Valley, a poorly 
exposed section reveals about 250 feet of strata, mainly reddish sandy 
shales, between the ‘“‘saurian conglomerate” and the uppermost 
Pennsylvania limestone. On Grand River about 1 mile above the 
Moab ferry the ‘‘saurian conglomerate” reappears above the level 
of the river, and, as it rises gradually to the northeast for several 
miles, a larger and larger section of the pre-Dolores strata is exposed, 
but nowhere so far as our observations go, do the Pennsylvanian beds 
appear, all the sub-Dolores section belonging to the upper (Permian ?) 
series of the Carboniferous. ‘This is itself evidence of a great break 
immediately below the ‘‘saurian conglomerate.” That the break 
represents uplift and erosion producing angular unconformity is 
well illustrated on both sides of Grand River about 10 or 12 miles 
northeast of the ferry and just below the mouth of Castle Creek, a 
stream heading on the west side of the La Sal Mountains. Fig. 8 
(a5 ) 
