200 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



lateral valley of Plateau Falls the upper members of the Madison limestone 

 are well developed, exposing a thickness of nearly 400 feet of beds. They 

 have yielded Orthothetes inflata, found throughout the Madison limestone, 

 and JEudothyra baileyi var. wav'erlyensis, as yet known only in the upper 

 beds. On a low conical hill in the middle of the valley similar limestones, 

 carrying the same fossils, occur nearly horizontal, but northward they dip 

 to the east and north. They pass beneath the cherty limestones and red 

 beds of the Teton formation, which northward are also exposed along the 

 west base of Two Ocean Plateau, the summit being capped by breccias. 

 Near Crooked Creek the Madison limestone again comes in, inclined south- 

 ward, with the Teton beds apparently lying within a syncline of the 

 Carboniferous beds. 



Between Crooked and Sickle creeks a prominent bold bluff of lime- 

 stone, facing westward, shows several hundred feet of Madison, which still 

 farther north passes by gradual transition into siliceous limestones and 

 quartzites. According to Mr. W. H. Weed, the latter beds belong to the 

 overlying Quadrant quartzite. This long strip of partially exposed sedi- 

 mentary strata indicates much folding and faulting, and in places excessive 

 compression of strata. Geologically it is of much interest, as it is probably 

 a remnant of an old mountain range, now for the most part submerged 

 beneath a vast pile of volcanic ejectamenta, which, resting upon the nneA^en 

 surfaces of the sedimentaiy beds, caps their highest summits and stretches 

 eastward for 50 miles across Two Ocean Plateau and the Absaroka Range. 

 Bluish-gray limestones again appear from beneath the breccias upon the 

 east side of the Absaroka Range, in a high bluff near the mouth of Stink- 

 ingwater Canyon, carrying Seminula humilis, Spirifer subattenuatus, Spirifer 

 striatus var. madisonensis. They mark the limestone as being a part of 

 the Madison formation, which comes out from beneath the breccias on both 

 sides of the volcanic plateau. 



TWO OCEAN PLATEAU. 



Two Ocean Plateau forms the most western oiitlier of the massive beds 

 of agglomerates that go to make up the Absaroka Range. It presents an 

 imposing pile of volcanic ejectamenta, rising 10,000 feet above sea level 

 in its most elevated portions. The highest portions lie to the eastward, 

 with a gentle dip toward the submerged range which rises here and there 

 above the plateau along the east side of the Snake fault. The plateau 



