376 PLEASANT WA YS IN SCIENCE. 



valley to more than twenty-five feet above the ordinary 

 level" But perhaps the most remarkable evidence of the 

 tremendous nature of this cataclysm is to be found in Lyell's 

 statements respecting the condition of the region nineteen 

 years later. " I found the signs of devastation still very 

 striking," he says ; " I also particularly remarked that the 

 surface of the bare granite rocks had been smoothed by 

 the passage over them of so much mud and stone." Pro- 

 fessor Hubbard mentions in Sillimaris Journal that "in 

 1838 the deep channels worn by the avalanches of mud 

 and stone, and the immense heaps of boulders and blocks of 

 granite in the river channel, still formed a picturesque feature 

 in the scenery." 



It will readily be understood that when destruction such 

 as this follows from landslips along the borders of insigni- 

 ficant rivers, those occurring on the banks of the mighty 

 rivers which drain whole continents are still more terrible. 

 The following account from the pen of Mr. Bates the 

 naturalist, indicates the nature of the landslips which occur 

 on the banks of the Amazon. " I was awoke before sunrise, 

 one morning," he says, " by an unusual sound resembling 

 the roar of artillery; the noise came from a considerable 

 distance, one crash succeeding another. I supposed it to 

 be an earthquake, for, although the night was breathlessly 

 calm, the broad river was much agitated, and the vessel 

 rolled heavily. Soon afterwards another loud explosion 

 took place, followed by others which lasted for an hour till 

 the day dawned, and we then saw the work of destruction 

 going forward on the other side of the river, about three 

 miles off. Large masses of forest, including trees of colossal 

 size, probably 200 feet in height, were rocking to and fro, 

 and falling headlong one after another into the water. After 

 each avalanche the wave which it caused returned on the 

 crumbly bank with tremendous force, and caused the fall 

 of other masses by undermining. The line of coast over 

 which the landslip extended was a mile or two in length ; 

 the cud of it however, was hid from our view by an inter 



