20*J 1HE WORLD, 



up by the avalanches of snow and ice, a reservoir or lake, was 

 thus formed, about half a league in length, two hundred feet deep* 

 and seven hundred feet wid. To lessen the mischief appre- 

 hended from the sudden bursting of this ice barrier, a channel 

 Was cut through the ice about 700 feet in length ; the flow of the 

 waters deepened this channel until nearly half the contents of 

 the lake were drained off* but on the approach of the hot season, 

 the remaining mass gave way with a trfmendous crash, and the 

 residue of the lake was emptied in half an hour. As the mass 

 of waters and floating ice swept through the narrow gorges, it 

 rose sometimes to an immense height, to burst again with in- 

 creased fury into the next basin, sweeping along rocks, forests, 

 bridges, and cultivated lands. Immense fragments of granite 

 rock were torn from the ancient soil and borne down ; one of 

 these, was sixty paces in circumference. 



The Deltas, or triangular sedimentary deposits which are formed 

 at the mouths of large rivers, often exhibit distinct marks of strati- 

 fication, and when they terminate in an extensive estuary, or arm 

 of the sea, the layer of mud brought down by the river is regu- 

 larly covered by a layer of sand, borne in and deposited upon the 

 mud at each returning tide. It is in this manner that the ripple 

 marks, and tracks of vermes, and molusces, are preserved. Every 

 one must have noticed, in walking along a sandy shore, at low 

 water, the undulating surface of the mud or sand, caused by the 

 little ripples in the water, and also the varied tracks of worms, 

 shell-fish, and birds. When a thin" layer of mud happens to be 

 deposited over these before the next return of the waves, a perfect 

 cast is thus obtained. Mr. Lyell, in his travels in North -America 

 mentions that he had obtained at Wolfville, on the Bay of Fundy, 

 thin slabs of the dried red mud, which presented perfect impres- 

 sions, on the upper side, showing the recent foot-prints of a small 

 sandpiper, as it marched over the soft -mud,"'which had after- 

 wards so much hardened in the sun as to become consolidated, 

 and upon the under surface exhibiting a. cast of the impressions 

 made in a previous deposit. The red sediment, or mud deposited 

 by the waters of the Bay, is obtained from undermining cliffs of 

 red sandstone, and soft red marl, and whenever the velocity of the 



