BELTRAMI ISLAND. 305 



the divide between the T;uuai-ack River and the West Branch of the Bow- 

 string- River (more couunonly called- the Big Fork), tribntary to Rainy 

 River, the height of the divide Ijeing only 15 to 20 feet above Red Lake. 

 Similar low swamp land forms nearly tlie whole northern and northwestex'n 

 shore of Red Lake and is crossed by this raih'oad survey continuously 

 along its first IS miles beyond Red Lake; but at a distance of 29 miles 

 from the lake the profile shows an ascent crossing the highest beach of 

 Lake Agassiz, which there is 1,215 feet above the sea. The next 17 miles 

 of the profile extend across the northeastern edge of a lax'ge island of Lake 

 Agassiz, rising ou that line to a maximum height of 1,283 feet, with a 

 moderately undulating drift-covered surface. In the next 15 miles, which 

 comprise the descent on a similar but smoother (Wft surface from the high- 

 est shore of Lake Agassiz to the War Road River, an affluent of the Lake 

 of the Woods, the profile crosses a succession of ten lower beaches of 

 Lake Agassiz, marking stages in the gradual uplifting of the land and 

 subsidence of the lake, their altitudes above the sea being 1,196, 1,172, 

 1,156, 1,143, 1,127, 1,116, 1,106, 1,099, 1,093, and 1,087 feet. 



These data show that Lake Agassiz in its highest stage had a large 

 island northwest of Red Lake, comprising- the headwaters of numerous 

 streams flowing outward from it to the Lake of the Woods, Rainy River, 

 Red Lake, the Red Lake River, and the Red River of the North. This 

 island had probably a diameter of 40 miles or more, with an area exceed- 

 ing 1,000 square miles, of which apparently more than half is in Beltrami 

 County, the portion farther west being chiefly in Marshall County, Minn. 

 For this tract, which had before been supposed to be comparatively low 

 and perhaps wholly beneath the highest level of Lake Agassiz, the name 

 Beltrami Island is proposed, in recognition of the exploration of the region 

 of Red Lake and the Julian or most northern sources of the Mississippi by 

 Beltrami in 1823.^ As Prof N. li. Winchell wrote in the historical sketch 

 here cited, this district "is still nearly as wild and imiuhabited as when 

 Mr. Beltrami passed through it." The limits of Beltrami Island are shown 

 approximately on Pis. X, XXII, and other maps in this volume." 



' Geology of Miimesota, Vol. I, 1884, pp. 44-50, with map. 



-Beltrami Island was first describetl iu the American Geologist, Vol. XI, pp. 423^25, .June, 1893; 

 and its earliest mapping was iu the Twenty-second Annual Report of the Geol. and Nat. Hist. Survey 

 of Minnesota, for 1893 (pub. 1894), Plato I. 



MON XXV 20 



