'204 NIAGARA FALLS. 



LETTER XLVII. 



Cataract of Niagara, September, 1820. 

 My Dear Sir, 



I believe that in a former Tetter I mentioned 

 the nature of the rocks which constitute the pre- 

 cipice of the Niagara Falls. The substratum is 

 a compact flesh red sand stone, infusible before 

 the blow pipe, but is rendered friable, and retains 

 its color. The upper strata are composed of 

 carbonate of lime, of immense volume and density. 

 This sand stone becomes brittle when exposed to 

 the atmosphere, and as it descends it increases in 

 fragility. About two miles north of the cataract, 

 there is a sulphur spring near the river, where the 

 sand stone is the lower stratum. At a considera- 

 ble distance down the DeviVs Hole, the same rock 

 appears, and also near the bottom of the great 

 ridge, or slope, atLewiston. The country above 

 ihe heights of Lewiston and Queenston is a vast 

 plain, from which there is an abrupt descent of 

 near three hundred feet, into another plain at 

 Lewiston, ond in which plain is Lake Ontario. 

 The upper slope is table lai#d, as well as the plain 

 below, and this produced the French denomina- 

 tion? of Upper and Lower Canada: The river 



