about the head of the Missouri, 6c. 235 
to fifteen hundred feet and incline high upon the sides of the 
mountains at an angle of 50° to 70°. They contain few fossils but 
these indicate rocks of the same age as those in the Black Hills. 
Along the Laramie mountains, from the Red Buttes to Pike’s 
Peak, apparently the same limestones are seen inclining against 
the sides of the elevated ridges at greater or less angles and on 
the opposite side of the axis sloping down to the Laramie plains 
the corresponding strata are seen, though leaning at much smaller 
angles, usually from 9° to 15°. Along the Sweet Water and 
Wind River mountains these rocks are highly developed and in- 
nite against the sides of the ridges of elevation as heretofore de- 
scribe 
Powder River, I observed at one locality a series of beds which 
indicated the presence of Permian rocks. These beds whieh are 
nh uposed of cherty magnesian limestone are very much like 
those already described in northeastern Kansas and contain in 
§teat abundance some of the same species of fossils as Myalina 
ratienuata and others. I have also seen similar limestones in 
Pet localities but no fossils were detected va though haying a 
; lan appearance they may belong to the upper portion 
the Cabins y may g ee ieee 
_ The evidence is clear in many localities that prior to the de- 
Position of the Red Marls succeeding the supposed Permian, a 
bey great erosion of the surface of the Carboniferous rocks took 
Place. We find, for example, in many localities only a thin rep- 
Fesentation of the Carboniferous rocks and again a full develop- 
ment, one thousand to fifteen hundred feet in thickness. | 
