ST. JOHN.] HOBACK CANON AND JOHN DAY RIDGES. 189 
spurs defining beautiful amphitheaters eroded out of the Carboniferous 
limestones which constitute the main mountain ridge. The position of 
the fault may be closely located at this locality, but to the south, in the 
undulating plateau east of Station VII, it is not so clearly indicated, as 
seen from this point. 
From the above mentioned Laramie ridge an extensive view of the 
surrounding country is gained, showing the general geological features 
most clearly. The Bear River belt soon passes to the west side of the 
Hoback tributary, below the forks of which it is dimly traced in the 
rough slopes rising up on the John Day ridge. In the latter quarter a 
somewhat detailed section was obtained, showing the Jura-Trias and 
later deposits, which is incorporated in the section through Station V. 
This section commences near the forks of the stream, and is thence car- 
ried westward up the slope to the crest of the John Day ridge, present- 
ing the following stratigraphic details: 
Section across basin between Hoback Caton and John Day ridges. 
No. 1. Reddish and buff siliceous Carboniferous deposits, plating the 
west slope of Station V, Hoback Cajon ridge. 
No. 2. Triassic red sandstones, in which the valley of the creek is here 
excavated. This series is here made up of red sandstones and grayish 
red arenaceous shales, capped by a heavy bed of buff sandstone, dipping 
WSW., at an angle of 35°; 1,500 to 2,500 feet. 
No. 3. Soft, buff, brecciated, vesicular limestone, with calcite, forming 
a heavy ledge. Dip WSW., angle of 25°. 
No. 4. Rather hard, fragmentary, drab limestone, with Jurassic fos- 
sils. A heavy bed. 
No. 5. Drab, indurated and nodular calcareous shales, with Pentacri- 
nus, Gryphea, &e. 
No. 6. Blue, fragmentary, even-bedded limestone, with shaly partings, 
Jurassic fossiis. Dip 32°, WSW. 
No. 7. Red, partially indurated shales. 
No. 8. Blue limestone and drab, indurated calcareous shales, with 
Camptonectes, Gryphea, &e., 300 feet or more. 
No. 9. Greenish sandstone and chocolate-red streaked shales, capped 
by gray, rusty-weathered sandstone, 100 to 150 feet. 
No. 10. Reddish shales, including a bed of light drab limestone and 
rusty indurated clay, overlaid by reddish and light gray sandstones, 
300 to 500 feet. 
No. 11. Dark shale, passing above into drab shales with indurated 
bands, 300 to 500 feet. 
No. 12. Heavy series of gray, buff and bluish, rusty and reddish- 
weathered sandstone, in places with ripple-markings, outcropping in 
ledges separated by intervening softer deposits, and exposed over an 
extent above a mile across. Dip 30° to 45°, WSW. 
No. 13. Light and dark drab and gray limestone, cherty and spar- 
seamed, containing Zuphrentis, crinoidal remains, Orthoceras, upper lay- 
ers, charged with Zaphrentis, Syringopora, and other Carboniferous fossils. 
Dip 10° to 40°, WSW., a vertical thickness of about 800 feet exposed in 
east face and crest of the John Day ridge, 5 miles north of Station VIII. 
The lower members of the foregoing section are clearly referable, by 
their fossils and lithology, to the Jura and Trias. But the series above 
the black clays, No. 11, including a vertical thickness of a few thousand 
feet, are doubtfully referred in part to the Cretaceous, but mainly to a 
later period, or the Laramie, possibly including early Cenozoic deposits. 
