22 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



first spring storm covers these with sand, and in a few 

 weeks the vigorous vegetation of a short but active 

 summer binds the whole together by a network of the 

 roots of bents and willows. Quantities of drift-sand pass 

 before the high winds into the swamp behind, and, 

 weighing down the flags and willow-branches, prepare a 

 fit soil for succeeding crops. During the winter of this 

 climate, all remains fixed as the summer left it ; and as 

 the next season is far advanced before the bank thaws, 

 little of it washes back into the water, but, on the con- 

 trary, every gale blowing from the lake brings a fresh 

 supply of sand from the shoals which are continually 

 forming along the shore. The floods raised by melted 

 snows cut narrow channels through the frozen beach, by 

 which the ponds behind are drained of their superfluous 

 waters. As the soil gradually acquires depth, the balsam- 

 poplars and aspens overpower the willows, which, how- 

 ever, continue to form a line of demarcation between the 

 lake and the encroaching forest. 



" Considerable sheets of water are also cut off on the 

 north-west side of the lake, where the bird's-eye limestone 

 forms the whole of the coast. Very recently this corner 

 was deeply indented by narrow, branching bays, whose 

 outer points were limestone cliffs. Under the action of 

 frost, the thin horizontal beds of this stone split up, cre- 

 vices are formed perpendicularly, large blocks are de- 

 tached, and the cliff is rapidly overthrown, soon becoming 

 masked by its own ruins. In a season or two the slabs 

 break into small fragments, which are tossed up by the 

 waves across the neck of the bay into the form of narrow 

 ridge-like beaches, from twenty to thirty feet high. Mud 

 and vegetable matter gradually fill up the pieces of water 

 thus secluded ; a willow swamp is formed ; and when 

 the ground is somewhat consolidated, the willows are 



