MISCELLANEOUS MENERAL8. 9 II 



the composition of the bed of the main stream, with which the waters Waters of the 

 passing rapidly and in large volume cannot come very often or inti- and Red 

 mately in contact. Probably more than half of the water of this river vl 

 is derived from the Rat, Roseau and Red Lake Rivers and other streams 

 flowing from the wooded and marshy country to the east, and this it 

 may be supposed does not differ much from that found in the rivers 

 flowing from woodland country in eastern Canada. This country is 

 also covered with drift deposits of glacial and post-glacial age, and the 

 streams seldom or never flow over solid rock. The tributaries from 

 the west, including the Shayenne, the Pembina and numerous smaller 

 rivers, are from a region which may be regarded as almost altogether 

 open prairie, and is subject to a rainfall considerably less in amount 

 than that in the east. These streams flow in part over glacial and post- 

 glacial deposits, but in part also over the underlying Cretaceous rocks, 

 of which the shales and clays of the Fort Pierre group cover the most 

 extensive area. Springs, the waters of which come in contact with the 

 Cretaceous rocks also, doubtless feed the tributaries. The Cretaceous 

 shales contain a considerable proportion of disseminated pyrites, which 

 latter when exposed to atmospheric influences undergoes decomposition, 

 ultimately giving rise, in the presence of the calcium carbonate con- 

 tained in the rocks, to the formation of gypsum, with which mineral — 

 generally in the crystalline form of selenite — many of the beds are in 

 consequence charged. There are also on this side of the Red River, 

 several springs impregnated with common salt ; these resemble those 

 of the Manitoba Lake district, and are probably like them derived from 

 the underlying Devonian rocks. Springs of this character are known 

 on the Salt River, south of the Pembina, and it was previously 

 attempted to utilize these as a source of supply of salt. Similar 

 springs are said also to occur on the Scratching River. 



The country drained by the Assiniboine resembles in most points 

 that described as giving rise to the other western tributaries of Red 

 River. By some of the eastern branches of the upper part of the 

 Assiniboine, from Riding and Duck Mountains, a certain amount of 

 woodland drainage is derived ; but by far the greater part of its tribu- 

 taries bring to it the drainage of prairie land, with a comparatively 

 small rainfall, and in which the saline matters would therefore be 

 supposed to exist in a more concentrated form. Though a compara- 

 tively small portion of the total length of the streams can flow in actual 

 contact with the underlying Cretaceous rocks, there is reason to believe 

 that in the prairie region west of the valley of the Red River, a great 

 part of the drainage of the country passes below the drift deposits along 

 the surface of the undelying rocks, and this being brought very inti- 



