266

B. N. A. BOUNDARY COMMISSION.

become river channels, but, in most cases they seem to have beennow long disused. This may arise either from a gradual decrease in theamount of flowing water, and in the intensity of the spring floods; orfrom an increasing scarcity of timber capable of forming obstructions, inthe regions traversed by the streams, which seems on other grounds tobe undeniable.

614. The Red River is still not far below the level of its borderingprairie, and from the fixed elevation of its out-hill in LakeWinnipeg, cannotbe lowering its bed appreciably, though the bordering prairie is no doubtgradually gaining somewhat in height from the sediment deposited inseasons of flood. The course of the river is exceedingly tortuous, andit is yearly becoming more so. An examination will show that all theconcave sides of the bends are being oaten away by the stream, and thestumps of old half-buried oak, and elm trees, being there exposed; while theopposite, or convex sides are almost invariably gaining by the addition ofbanks of sediment, which as soon as they are formed are taken possessionof by thickets of young willows, and consolidated by their roots. Whenthis process has been carried to an extreme, it is naturally remedied bythe breaking of the water across one of the narrow nocks separatingtwo of the bends, during some period of excessive flood, and the formationof a new course. I do not know of any very modern instance of this, butold portions of the river-channel, may frequently be observed formingponds and small lakes on the jn'airic, sometimes more than a mile fromthe present stream. Those, like the parent river, may bo fringedwith trees, and are generally surrounded by a dense growth of reeds, andfilled with rank aquatic vegetation.

615. The floods of this river, arising from the melting snow in spring,are intensified by its northern course; the sources being broken up and inflood, while the ice at its mouth is still quite firm. Extensive ice-jamsarc apt to form, and a small increase in the elevation of the waterabove the banks, serves to overflow a great area of 'country. Thesilting up of the mouth of the river, may also, as has been suggested,have something to do with'thc recurrence of great floods at somewhatregular intervals, and may require some such natural paroxysm forits remedy.

616. The systems of ramifying collides with gently sloping grassybanks, but with neither brooks nor regular stream courses, when seenduring the dry weather of summer, may seem to require for their expla-