3i 



The river north of the mouth of the gorge has an 

 average width of about 2,000 feet (610 m.) and an aver- 

 age depth of 45 feet (13-7 m.). The deepest point, 183 

 feet (55-8 m.) (Spencer), is opposite Queenston. The 

 deepest channel over the bar is about 25 feet (7 -6m.) 

 deep. 



The whirlpool is 1,700 feet (518 m.) wide between 

 rock cliffs. The mouth of the old gorge in the embayment 

 south of St. David is one mile (i-6km.) wide, but con- 

 tracts to five-eighths of a mile (i-okm.) at a point one 

 half mile (-8km.) within the mouth, where the last of 

 the rock cliffs in the embayment are seen. 



The accompanying map of Niagara Gorge shows the 

 division points where the gorge is divided into sections 

 and the relation of the sections to each other. 



THE WHIRLPOOL AND THE BURIED ST. 

 DAVID GORGE. 



It has long been recognized that the rock basin of the 

 whirlpool is older than the rest of the gorge and has had 

 a different history. It is a buried, drift-filled gorge of 

 inter-glacial age. The walls surrounding it on the east and 

 west sides are rock cliffs, like those in the gorge immedi- 

 ately above and below. But on the north and northwest 

 sides the entire wall from the top down to an undetermined 

 depth below the water is composed of sand and gravel, 

 stony clay and boulders, all being loose drift of a later 

 age than the rock gorge itself. Bowman creek descends 

 to the whirlpool from the upland about a mile to the north- 

 west and has cut a deep ravine in the soft sediments, 

 reaching far below the ledges that mark the top of the 

 ancient gorge. The ravine itself lies mainly along the 

 western side, for the western rock wall and cliffs are ex- 

 posed for some distance. The east side of Bowman ravine 

 however, shows no rock, but is composed entirely of drift, 

 even down where the creek enters the whirlpool. Frag- 

 ments of the rock cliffs on the two sides of the ancient 

 gorge run a short way north-northwest from the whirlpool 

 showing the direction in which the buried gorge extends. 



South of the village of St. David there is a strongly 

 marked re-entrant in the front of the escarpment, the 

 head of which shows no rock for about a mile, but is a 



