PLANTS FROM THE BIG HORN MOUNTAINS OF WYOMING, 
By J. N. Rose. 
INTRODUCTORY STATEMENT. 
Mr. Frank Tweedy, of the Geological Survey, made a small but very 
interesting collection of plants in the Big Horn Mountains of Wyoming 
in 1893. No attempt was made by Mr. Tweedy to get a complete rep- 
resentation of the flora of this region, which is extremely rich and 
varied. His collecting was merely incidental to his other work, and 
was done chiefly while reaching some mountain peak or returning from 
it tocamp. His plants, therefore, are chietly alpine. 
The Big Horn Mountains begin near the middle of the northern 
boundary of Wyoming, running in a northwest and southeast direction 
for about one-third the distance across the State. The mountains are 
very much broken and very rugged on the flanks, and there are few or 
no trails. They contain many peaks which are 9,000 to 11,000 feet in 
altitude. 
Mr. Tweedy speaks of the geology and topography of this region as 
follows: 
The Big Horn range where crossed has a width of 35 miles, trending to the north- 
west, with elevations varying from 5,000 feet at base to 11,000 feet on the highest 
summits. The range gradually slopes to the northward, running out in southern 
Montana, and about 12 miles south of our route rises to the rugged summits of Cloud 
Peak, 13,500 feet in elevation. The range is a broad anticlinal arch, presenting a 
wide Archean core, with narrow bands of sedimentary formation on the east and 
west flanks dipping very abruptly to the plains below, 80 as to form exceedingly 
precipitous blufis and slopes of from 1,500 to 2,000 feet. The interior presents a 
marked contrast, being generally composed of broad, flat ridges and summits cov- 
ered with beautiful grassy parks and patches of heavy timber. Southward the 
country becomes more rugged and broken, and the timber more frequent and denser. 
Great areas have been swept over by forest fires, making traveling exceedingly slow 
and difficult. The drainage of the interior is peculiar in that the streams have 
porth and south courses before they break through the rim in deep, rough, and 
often inaccessible canyons. 
Mr. Tweedy fitted out near the town of Sheridan, going into the 
mountains up Little Goose Creek, crossing the divide near the head 
waters of the Big Goose Creek, and then going down Shell Creek into 
the Big Horn Basin. 
His stations in the Big Horn Mountains are between longitude 107° 
and 107° 30/ and latitude 44° 30’ and 44° 40’, chiefly on the head waters 
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