ON THE GEOLOGY AND NATURAL HISTORY 
26 
were observed in this locality. The following section represents the different beds in de¬ 
scending order: 
1. A hard compact fine-grained yellowish limestone, of an excellent quality, passing down into a yellow calcareous 
sandstone somewhat soft and friable. Fossils: Spirifer Rockymontana, Spirigera like S. sv.htileta, 
Cyrtoceras, &c. 50 feet. 
2. Loose layers of very hard yellow arenaceous limestone with a reddish tinge; then a bed 6 to 8 feet in thickness 
of very hard blue limestone, passing down into a repetition of loose layers of yellow arenaceous limestone. 
The whole contains vast quantities of comminuted crinoidal remains with corals and several species of Bra- 
chiopod i. 40 feet. 
3. Variegated calcareous sandstone, gray and reddish quartzose with particles of mica. Some portions are very 
compact and silicious, others a coarse friable grit, others a conglomerate. Fossils : Lingula prima, Lin¬ 
gula undetermined, Obolus and fragments of Trilobites. 30 to 50 feet. 
4. Metamorphic rocks standing in a vertical position for the most part. 
The main ridge of upheaval seems to have a bearing about 40° west of north. The 
principal ridges appear to be nearly parallel, but the smaller upheavals cannot be brought 
into any system. I think the red granite at this locality contains more mica than usual, 
and might therefore be called micaceous granite. In other respects it presents much the 
same characters as that which forms the main body of Laramie peak and Rawhide peak. 
Here also we noticed a bed of clay or talcose slates, eight to ten feet in thickness, attached 
to and passing down into the granitic mass. Alongside of the slate, and evidently of more 
recent origin, is a bed of compact silicious rock, with stratification distinct, and differing 
very little from the quartzose rocks seen on the Platte. 
The Potsdam sandstone presents a great variety of lithological characters. In many 
localities it assumes the form of a conglomerate of more or less water-worn pebbles, mostly 
whitish crystalline quartz, but representing every variety of the metamorphic rock beneath. 
The pebbles vary in size from an eighth of an inch to four inches in diameter, but the 
greater part are from one half of an inch to two inches in diameter, cemented together 
with quartzose sand. Some of the pebbles are scarcely worn, others are perfectly smooth. 
At the locality where the last section was taken, the sandstone is of a gray color, tinged 
with red at the base; but, passing up, it becomes more ferruginous until its color is a dark 
red, and its texture a coarse-grained friable sandstone, with many quartzose and micaceous 
particles and some calcareous matter. Seams two to four inches in thickness are very 
nearly composed of comminuted fragments of shells, comparatively few being sufficiently 
perfect to be identified. 
The metamorphic rocks were not altogether vertical to-day, but dipping at an angle of 
70° to the southeast. We travelled about nine miles through the metamorphic rock, 
Potsdam sandstone and Carboniferous limestone. A section taken on the southeastern 
