82 



Types of Aquatic Environment 



minute icicles are forming and their tips are being broken 

 off by the oscillations of the current. These broken 

 tips constitute 

 the rubble. 

 They are some- 

 times remark- 

 ably uniform in 

 size those form- 

 ing when this 

 picture was 

 taken were 

 about the size 

 of pea s a n d 

 though small 

 they are the 

 tools with which 

 the current does 

 its winter clean- 

 ing. In the 

 ponds formed by 

 damming rapid 

 streams this rub- 

 ble accumulates 

 under the solid 

 ice. 



"Anchor ice" 

 forms in the 

 beds of rapid 

 streams, and 

 adds another 

 peril to their in- 

 habitants. The 

 water, cooled . 



, 1 /i r FIG. 23. The ice veil on Triphammer Falls, Cornell 



DelOW trie ireez- University Campus. The fall is at the left, the 



in " point bv COn- Laboratory of Hydraulic Engineering at the right 



* . . .. ' . in the picture, the only open water seen is in the 



tact With the air, foaming pool at the foot of the fall. 



. 



