UTAH ACADEMY OF SCIENCES 37 
Out of a total of twenty-six individuals there are 
twenty-one Pelecypoda, one Gastropoda, two Cephalopoda, 
one Articulata, one Crinoideae. The Pelecypoda greatly out- 
number all the rest. There are nineteen different genera, 
all indicative of a marine habitat, the Crinoid and Cephal- 
opoda especially characteristic of such. Of these, seven- 
teen species are characteristic of the Jurassic, while the 
remainder either begin in the Jurassic or earlier. 
It is plain then that our strata in Utah are Jurassic, but 
the data is insufficient to say with assurance that they are 
the Middle Jurassic as found in other areas. The exact 
correlation of the subdivisions of the Jurassic of Utah with 
those of identified localities is a problem yet to be solved, 
and a worthy field for original research. 
After this subsidence and the deposition of the Lime- 
stone series, a slight rise seems to have occurred and a red 
arenaceous shale was deposited in these lagoons. Along 
with them ferric oxides were thrown down, with one ex- 
ception. In the case of the Green Sandstone and Shales, 
Glauconite took the place of the oxides. As concentra- 
tion proceeded, Gypsum, a characteristic of the lower half 
of the period, was deposited. However, the process of con- 
centration did not continue long enough to deposit any 
salt in this locality, at least. The Upper portion of the 
Middle Jurassic became more and more arenaceous, and the 
lagoons gradually filled up with a sandstone-shale complex. 
As this filling continued we find shore deposits, and 
it is here that I have drawn the line between the Middle and 
Upper Jurassic Series. 
The base of the Upper Jurassic is a siliceous conglom- 
erate, consisting of water-worn pebbles seldom larger 
than a good sized hen’s egg, and grading from that down 
to sand grains. Immediately overlying this is a calcareous, 
argillaceous conglomerate. This is characteristically varie- 
gated. The pebbles are small, waterworn, and generally 
coated with a thin flim of a black manganese oxide. It is 
in the lower part of this conglomerate that the majority 
of the vertebrate remains of the Jurassic are found. These 
remains are found more or less throughout this Complex. 
