384 



SCIENCE 



[N. S. Vol. XXVIII. No. 716 



I discovered in 1888. The Tolume of the Erie 

 drainage is now found to have been only 15 per 

 cent, of the present discharge of Niagara River. 

 The change mentioned consisted of a new force 

 breaking through the hard sandstone floor of the 

 river to a great depth, as found by the new sound- 

 ings, and making a much greater channel than the 

 united falls had been able to produce. This in- 

 creased force arose from the addition of the full 

 discharge of all the upper lakes, which is now 

 thus established to have taken place, when the 

 falls were at this point. 



Throughout this lower section of about three 

 miles, the work performed by the upper cataract 

 has been determined. Therefore, by applying the 

 laws of erosion, it became possible to calculate 

 the approximate age of this section of the gorge. 

 Had it been necessary to depend upon the work 

 of the second and third cataracts, it is hardly 

 likely that any reliable determination could have 

 been made. The results show that a period of 

 35,500 years was required for the recession of the 

 falls in this lower section or 39,000 years in the 

 whole length of the canyon. 



The turning of the Huron drainage into Lake 

 Erie occurred 3,500 years ago, and it is 3,000 

 years since the falls reached the whirlpool. They 

 were passing the site of the Whirlpool Kapids 

 from 2,500 to 2,000 years ago, while the rapids 

 themselves were completed less than 300 years 

 since. 



Pre-glacial Erie Outlet. 



The Erie Basin formed a depression in the 

 Devonian shales, bounded on the north by a nar- 

 row ridge, capped by Comiferous limestone. This 

 was faced on its northern side by a low escarp- 

 ment, descending to the basin in the soft rocks of 

 the Salina formation, which was bounded on its 

 northern side by durable Niagara limestone. The 

 escarpment and basin mentioned are now leveled 

 over by drift formations. Beyond the Niagara 

 limestone there was again a parallel trough of 

 the Ontario basin, excavated out of soft Medina 

 shales. Such was the pre-glacial character of the 

 Niagara peninsula between Lake Erie and Lake 

 Ontario. 



Many years ago I foimd that the ridge of 

 Niagara limestone, at the head of Lake Ontario, 

 was trenched sufficiently deep to at least draw 

 water from the Erie basin. Another trench to a 

 depth of 28 feet below the surface of that lake 

 occurs along the Welland Canal. 



Upon investigating the character of the rock- 

 bound basin at Niagara Falls, I found that it did 



not lead to the north, as was supposed, but 

 rapidly widened and deepened to the southwest- 

 ward, even to one hundred feet below the surface 

 of Lake Erie. Determined to find whither this 

 pre-glacial valley led, I collected the records of 

 borings, and made other borings, with the result 

 that a deep pre-glacial valley was discovered cut- 

 ting the Corniferous limestone for a breadth of 

 less than two miles, immediately east of Lowbank 

 Post Office, and crossing the Salina basin, and 

 again trenching the ridge of Niagara limestone 

 (here forming a canyon) filled with drift, but 

 partly reopened by the modern streams, just west 

 of De Cou Falls, the inner canyon being some- 

 what more than a mile, and the outer more than 

 two miles in width. With allowance for the 

 measured post-glacial uplift, this buried valley, 

 revealed by borings at almost every mile, was 

 sufiiciently deep to drain the pre-glacial Erie 

 valley, receiving, as it did, the ancient Ohio and 

 Alleghany rivers as tributaries. These gorges 

 through the hard ridges between the buried val- 

 leys resemble the courses of streams crossing the 

 Appalachian ridges. The discovery of this ancient 

 water course is one of the most completely dem- 

 onstrated of all those bringing to light the great 

 changes of drainage since pre-glacial days, and is 

 a lesson for further research. 



This closed the sectional meeting. 



The excursion to Mount Ascutney, Wednesday, 

 July 1, was shared by twenty-two members. A 

 number accompanied Dr. Daly in a drive about 

 the base of the moimtain and to Little Ascutney 

 to examine the igneous rocks and contact phe- 

 nomena. The others ascended the principal height. 

 In the view from the summit the oldest recog- 

 nizable peneplain of the region was studied and 

 certain differences of opinion as to its character 

 were developed. To some of those present, the 

 reduction of the surface toward a general pene- 

 plain appeared less complete than had been ex- 

 pected, and the appearance of the topography 

 suggested that of certain mid-Tertiary slopes and 

 heights. 



From the excursion to Mount Ascutney mem- 

 bers of Section E returned to Hanover to take 

 part in the general exercises, including the trip 

 to the Corbin Game Park on Thursday, July 2. 



On Friday and Saturday a number proceeded 

 from Hanover to Littleton, N. H., under the 

 guidance of Professor Hitchcock, and examined the 

 stratigraphy of the Silurian rocks, from which 

 trilobites and brachiopods were collected. 



Bailet Willis 



