896 N. H. W1NCHELL ON THE RECESSION 



and of small size, near the foot of the cataract in the west 

 channel. 



Beltrami in 1823. — Only distinctly mentions an island in the 

 Palls, and an island of sandstone below, with maples. 



Keating in 1823. — An island in the river both above and below 

 the cataract, separating it into two unequal parts, the eastern 230 

 yards, and the western 310 yards wide, the island itself being 100 

 yards wide ; below the Fall the river contracts to about 200 yards. 



Featherstonhaugh in 1835. — The average fall is not far from 20 

 feet ; an island, 450 yards long, divides the fall unequally ; the 

 channel on the east of the island 220 yards wide, that on the west 

 450. 



By combining and adjusting these statements with each other, 

 a continued record is found of the appearance of the Palls since their 

 discovery, and by the present existence of islands in the channel 

 and in the cataract the position of the Palls at certain dates may 

 be satisfactorily established. When they were discovered by Henne- 

 pin they were divided by Spirit Island, and were much higher than 

 now, owing probably to the contraction of the gorge below the 

 falls, as mentioned by Keating in 1823. The gorge across Spirit 

 Island has a width of 1350 feet, determined by a system of trian- 

 gulation by Prof. Ehame, of the University of Minnesota ; while 

 the width of the gorge, including Hennepin Island, is 1700 feet at 

 the point where the Palls were in 1856. Below Spirit Island the 

 gorge becomes still narrower. When Carver saw the Palls in 1766 

 they were just leaving Spirit Island and entering on Hennepin 

 Island. The many inaccuracies in Carver's description, and in his 

 illustration, render it almost certain that he wrote his account and 

 drew his sketch at some time subsequent to his visit. His use of 

 the past tense in the expressions, "on which greiv a few ragged 

 hemlock and spruce trees," " that appeared to be about five or six 

 feet broad," and " ivas full of eagles' nests," seems to confirm this 

 supposition. The island which Carver's engraving shows above the 

 Palls must be intended for Hennepin's Island, as he remembered it, 

 which now divides the Palls ; but it is very much out of the right 

 position even to represent any island ; while the " oblique rock " 

 which he noted in the brink of the east fall was the extremity of 

 the submerged toe of the same island. The rocky substructure of 

 an island would extend in all directions beyond the actual visible 

 island, and would appear, at the proper time, as an isolated project- 

 ing rock as the earthy covering gave it more and more protection 

 by dividing the current. At that time the water of the river com- 

 pletely surrounded the visible portion of Hennepin Island, above the 

 brink of the Falls, as Carver naturally represents. The projecting 

 rock was " oblique," because the limestone rock falls off in rhomboidal 

 masses, governed by the preexisting jointage-planes, thus causing a 

 zigzag outline even across the whole brink, as later fully described 

 by Keating. Carver's estimates of distance are very inaccurate. 

 He mentions " about 600 feet " as the width of the Palls when he 

 saw them ; but they must have been 1400 feet, as determined by 



