NIVERYILLE BEACHES. 473 



river and exti^nds about, 1 mile, crosse8 three laeach ridges <if graA^el and sand 

 that together represent the single Niverville beach fartlier south. Tlieir 

 heights, in order from west to east, are 95, 90, and 80 feet above Lake 

 Winnipeg, or SOo, SOO, and 790 feet above the sea. Two Niverville stages 

 of Lake Agassiz, or we may say three, are thus shown to have lieen caused 

 here by the northward uplifting of the land, with intervals of f) and 10 feet 

 between its stages of temporary repose. 



All the shore-lines described in this chapter and in the two jireceding 

 chapters must be referred to the glacial Lake Agassiz, held on its northern 

 side by the barrier of the waning ice-sheet; for the country north of Lake 

 Winnipeg presents no barrier of land through which the Nelson River has 

 cut its passage so high as the Niverville beach. Lake Winnipeg and its 

 outflowing stream huve been lowered by erosion onl}- about 20 feet from 

 the level of the beach noted by Hind thirty-five j-ears ago.' 



See Cha ter V, p. 221. 



