A. G. LEONARD 



THE PEE-CAMBRIAN GRANITE 



Many deep wells in the Red River Valley have reached granite, 

 and these show that beneath the drift and older formations the 

 valley is underlain by crystalline rock which is probably of Archean 

 age, though like some of the Minnesota granite it may possibly be 

 Keweenawan. The granite is struck at depths ranging from 255 to 

 470 feet, and its surface is quite uneven. It is overlain in some 

 places by glacial drift, in others by Cretaceous shale and sandstone, 

 and in the northern portion of the valley by Paleozoic strata. 



In going from south to north in the valley the granite has been 

 encountered in wells at various depths as follows: Wahpeton, 470 

 feet; Moorhead, Minnesota, across the river from Fargo, 365 feet; 

 well 7 miles north of Moorhead, 255 feet; Casselton, 20 miles west 

 of Fargo, 455 feet; Grand Forks, 385 feet; East Grand Forks, 

 Minnesota, 325 feet; University, two miles west of Grand Forks, 

 425 feet; and Grafton, 40 miles north, 903 feet. The well at 

 Rosenfeld, Manitoba, 14 miles north of the international boundary 

 and 1 1 miles west of the Red River, reached the granite (or gneiss) 

 at 1,035 feet.^ In the Soldiers' Home well at Lisbon, a few miles 

 west of the Red River Valley on the Cheyenne River, the granite 

 was struck at 785 feet. The Moorhead well, which was drilled by 

 the city in search of water and gas, is notable on account of the 

 distance it went in the granite, the record being as follows: 220 feet 

 of alluvial and lacustrine silt, 145 feet of bluish and greenish shales, 

 with beds of sand, probably Benton, and 1,385 feet of granite and 

 gneiss, thus reaching a depth of 1,750 feet.^ 



THE PALEOZOIC SYSTEMS 



During at least a portion of this era the Paleozoic sea appears 

 to have covered North Dakota, and in its waters were deposited 

 the limestones, shales, and sandstones of the Cambrian, Silurian, 

 and Devonian. Two or more of these systems outcrop not far 

 to the north in Manitoba, to the east in Minnesota, and to the south 



' G. M. Dawson, "On Certain Borings in Manitoba and the Northwest Territory," 

 Trans. Royal Soc. Canada, IV, sec. 4 (1886), 85-91. 



^ Warren Upham, U.S. Geol. Survey, Mono. No. 25, 1896, p. 556. 



