Science, Geology and Physics 



a buried valley, and no connection with the Whirlpool was 1908 

 attributed to it. Later it was supposed that the break in the 

 side of the Gorge, and the one at St. Davids, were parts of one 

 and the same course of some pre-glacial stream. This supposition 

 has been proven by the course having been traced through most 

 of its distance by the wells sunk in the region. Later this inter- 

 pretation of the facts found was destined to furnish further 

 explanations. The question at once arose: How far and where 

 did the upper course of this ancient valley extend? If it had cut 

 across the course of the modern river, there would have been a 

 break in the continuity of the cliff somewhere on the opposite side 

 of the Gorge ; but this can nowhere be found to be the case. The 

 upper course of this ancient channel, therefore, must have coin- 

 cided with that of the present channel. When, then, the Falls 

 had receded to the side of the present Whirlpool, it reached a 

 point where the greater part of its work had been performed. 

 From here to whatever distance the upper course of the ancient 

 river extended, the only work to do was to remove the loose 

 gravel and boulders with which the glacier had filled its channel. 

 This, of course, was effected much more rapidly than the wear- 

 ing away of the hard limestone bed. Just what was the depth, 

 and how far this old deserted valley extended, it is almost impossi- 

 ble to estimate. These changes are some of the most potent 

 with which one must reckon in any calculation of the time since 

 the beginning of Niagara's history. However, some work has 

 been done in this line; and a broad field is still open for future 

 investigation. 



Spencer, Joseph William Winthrop. Changes in the recession 1908 

 of the Falls of Niagara. (Science n.s., Sept. 18, 1908. 28:383-384.) Spencer 



"A mere summary of some of many chapters required in describing 

 phenomena which bring to light the changing features of Niagara Falls." 



Spencer, Joseph William Winthrop. Revision of the age of 



Niagara Falls. (Science n. s., June 12, 1908. 27:925-926.) 



Resume of paper read at the Geological Society of Washington, April 8, 

 1908. 



683 



