130 HalVs Remarks on Niagara Falls 



the height ; unless from its thin bedded character it continued 

 to recede faster, and thus continue a rapid. In this case, 

 there would be a fall of one hundred and twenty feet at the 

 end of the first mile {i. k.) ; and one of eighty feet (o. p.) at 

 the end of the second mile. 



At this period, then, we are to contemplate the cataract of 

 Niagara as having receded two miles, the shale having disap- 

 peared beneath the river, and the cascade presenting a solid 

 wall of limestone eighty feet high, and a rapid of forty or fifty 

 feet (o. m.) beyond. The recession would then go on very 

 gradually, and so soon as masses from this clifi" have fallen 

 down to fill up the river bed, as they inevitably will in a 

 great measure, then the base will be protected so effectually 

 that little influence will be exerted by the force of the water. 

 Eventually, however, the clifl* will be broken down, and huge 

 fragments piled up below, until the cataract will be nearly 

 lost amid them. This state of things will continue for a long 

 time, the height gradually diminishing, till the river has cut 

 its way back for two miles further, when there will be no 

 thick bedded limestone above water, and the higher beds will 

 form a rapid as before. 



This point of meeting, between the surface of the river 

 and the top of the thick bedded limestone, will be about one 

 hundred feet lower than the summit of the present cascade, 

 and as there will be forty feet of rapids in the thin bedded 

 limestone within a short space, as there now is, it follows that 

 there will be added to the descent of the river beyond the 

 rapids, one hundred feet more than at present, as the surface 

 of the limestone has dipped to that amount. The whole fall 

 in the river at that time, from Lake Erie to the point of junc- 

 tion between the limestone and water below the rapids {h. o.), 

 will be about one hundred and sixty feet. The distance 

 between this point and Lake Erie is occupied by nearly uni- 

 form soft layers, and after a partial wearing down of the lime- 

 stone forming the rapids, the descent will be equally distributed 

 over the whole extent of sixteen miles, giving a uniform de- 

 clivity of about ten feet in the mile, or one third less than 

 the present declivity in the bed of the river from the falls to 



