NIAGARA AS A TIMEPIECE. 7 



escarpment, where there is a sudden descent of two hundred and 

 forty feet to the lower plain, that gradually slopes for eight miles 

 farther to the present shores of Lake Ontario, whose waters are 

 three hundred and twenty-six feet below the surface of Lake 

 Erie. 



The features of the plain which have a bearing upon the de- 

 velopment of the Niagara River are, a low ridge crossing the river 

 just north of the outlet of Lake Erie ; a comparatively level plain 

 underlaid by soft rocks, extending thence to near the head of the 

 rapids above the falls, north of which, to the brow of the escarp- 

 ment, the country rests upon hard limestones, with underlying 

 strata of soft shales and occasional layers of more persisting rocks. 

 These softer shales form the foundation of the country between 

 the end of the gorge at the brow of the mountain near Queens- 



FiG. 5. — Bird's-eye View of the Niagara District (Pohlman). The buried cliannel or 

 valley from the falls to the edge of the mountain at St. Da\'ids is about a mile and a 

 half broad, but it is not anywhere nearly as deep as the Niagara gorge. 



ton (and Lewiston) and Lake Ontario. The work of the river has 

 been to remove the soft rocks and undermine the thick and hard 

 capping limestones. The chasm of the Niagara River is simply 

 chiseled out of an elevated table-land, whose surface is a remark- 

 ably level plain, covered with towns, villages, and farms, extend- 

 ing apparently without a break until one is surprised at coming 

 suddenly upon the brink of an abyss, without meeting with the 

 sloping features which constitute the usual approaches to deep 

 valleys. The feature of the gorge with unbroken perpendicular 

 walls is shown in Figs. 6 and 7, which are characteristic forms of 

 modern canons. If the valley were of great antiquity it should 

 have been two miles or more in width, in place of a gorge of a 

 quarter of a mile wide, and it should have had scarcely any frag- 

 ments of perpendicular walls standing. Indeed, an old valley, 

 buried beneath some ninety feet of drift, does cross the course 



