Report of the exploring expedition from Santa Fé, New Mexico, to the junction of the Grand and Green Rivers of the great Colorado of the West, in 1859 under the command of Capt. J.N. Macomb. With geological report by J.S. Newberry.

TO JUNCTION OF GRAND AND GREEN RIVERS. 91
Section of the cliffs of Canon Pintado.
Feet.
1. Coarse yellow sandstone, floor of Sage-plain ------------------------- 200
2. Gray and green shales, interstratified with coarse gray sandstones and yellow
conglomerate —-------------- 250
3. Red and green shales, with bands of whitish and greenish sandstone, with silicifled wood and Saurian bones -------------------------------------— 350
4. Yellow and red massive calcareous sandstones -------------------------- 200
In the foregoing section No. 1 is the Lower Cretaceous sandstone forming the
surface-rock over all the country lying between the Sierra La Plata and Sierra Abajo.
A short distance back from the canon it is overlaid by patches of shale with Gryph.eas,
and therefore represents the surface of the Lower Cretaceous group. No. 2 is probably also Cretaceous, though here containing no fossils by which this question could be
~determined with certainty. A group of rocks, having similar lithological characters,
at the Moqui villages, lies between the red beds below and the massive leaf-bearing
sandstones above, and there contains Anmmonites percarinatus and other Lower Cretaceous fossils. As will be seen in the progress of our geological narrative, at intermediate points on the San Juan a thickness of several hundred feet of soft green sandstones and green sandy shales separates the coarse yellow sandstones (the floor of the
Sage-plain) from the red gypsiferous rocks below. Until fossils shall be discovered in
these beds, it will be impossible to draw any sharply defined line marking the base of
the Cretaceous formation; and since the strata are here everywhere conformable, it is
extremely doubtful whether any such line of demarcation exists in nature.
Saurian bones.-On the north side of the canfion just opposite our camp (26), in the
face of the cliff, about 250 feet above its base, I discovered the bones of a large Saurian.
Probably the greater part of the skeleton is still imbedded in the rock, as, although I spent
two days, with several assistants, in excavating at this point, the tools at our command
were too light for such heavy work as it proved to be, and we were compelled to
leave many bones, which we could see, but had not the means to extricate from their
envelopes. The special object of our efforts, the head, was not reached, but still
remains to reward some future geologist who shall visit this interesting locality, with
more time at his command and more adequate implements for rock excavation than
we possessed. The bones we obtained were mainly those of the extremities: a femur
entire; the greater part of a humerus; several of the phalanges of the-toes; portions of
the ribs, and other large and, to me, quite incomprehensible bones. All of these have
been placed in the hands of the distinguished anatomist, Professor Leidy, who will
make them the subject of a special report. The size of the animal, as indicated by
these bones, must have been very large. The femur taken out measured 30 inches in
length, by 4 in diameter, at its smallest part, the articulations being much thicker. A
portion of the scapula which was taken out was 22 inches long and 16 wide at the
broadest part, and this but a fragment.
Near the locality where the larger skeleton was found a part of a rib of a snmaller
individual was picked up, and on the opposite side of the valley a shapeless fragment
of a large bone was found at the foot of the cliff. From these facts it is evident that