THE GALLATIN MOUNTAINS. 33 



QUADRANT MOUNTAIN. 



The broad summit of Quadrant Mountain is an open and grass-covered 

 area, above which a bold pyramid formed of the red Teton sandstones 

 rises quite abruptly. Snow fields cover the summit in early spring and 

 remain through the summer, nourishing streams that flow in cascades over 

 the walls of the Pocket. The upper slopes, which lie beneath the cliffs of 

 white Quadrant sandstones, are dark with the lichen-covered ddbris from 

 the overhanging walls, while the slopes beneath are thickly timbered. The 

 summit of the mountain slopes northward with an angle of 3° to 4°, con- 

 forming very nearly to the bed of the rocks. The flatness of the mountain 

 top is clearly due to the resistant nature of the Teton limestones, as the 

 overlying clays and sandstones are rapidly removed by erosion. This 

 mountain block is of very simple stratigraphical structure. The beds are 

 slightly flexed, without faulting, and are undisturbed by intrusives. The 

 beds forming it are the Madison limestones, covered by the white Quadrant 

 quartzites overlain by the cherty beds of the Teton formation. The strata, 

 forming the mountain are clearly a continuation of those of Antler Peak and 

 Panther Creek Canyon; on the west the beds are seen to be connected with 

 those of Bannock Peak through the saddle of the amphitheater, while on the 

 north the Quadrant quartzites form the floor of Fawn Creek Valley and 

 pass under the slopes of Little Quadrant Mountain. Eastward the beds 

 end in a cliff and steep slope along that north-south line which separates 

 the sedimentaries of the range from the lavas of the plateau. The general 

 dip of the beds is a little west of north, about 8°, so that the slope of the 

 summit corresponds approximately to the dip of the beds. 



The summit of the mountain has been carefully examined. West of 

 the Pocket the cherty Teton limestone covers the surface, which, when 

 examined closely, is seen to be rough, gullied, and hummocked. The red 

 hill on the summit of the mountain, southeast of the Pocket, is composed of 

 the red Teton sandstones. This point is about 200 feet higher than the 

 surrounding summit. On the east, south, west, and northwest these beds 

 commence at the very foot of the hill ; on the northeast the area extends about 

 one-fifth of a mile farther. The general summit from the red point north 

 is formed of the Teton cherty limestone and its associated lingula-bearing 

 limestone, down to 9,200 feet, where the red beds again cover a portion of 



HON XXXII, PT IX 3 



