90 



SCIENCE. 



[N. S. Vol. V. No. 107. 



The Nipisdng-Mattawa River, the Outlet of the 



Nipissing Great Lakes. F. B. Taylor, 



Fort Wayne, Ind. 



When the waters of Lakes Superior, 

 Michigan and Huron were making the l^ip- 

 issing beach, their outlet was eastward 

 over the Nipissing pass at North Bay, On- 

 tario, to the Ottawa valley. This outlet 

 river is called the Nipissing-Mattawa River 

 and the three upper great lakes of that 

 time are called the Nipissing Great Lakes. 

 During the autumn just passed the course 

 of the outlet river was explored. The Nip- 

 issing beach is well developed at North 

 Bay at an altitude of about 700 feet above 

 sea-level. On the swampy col between 

 Lake Nipissing and Trout Lake it was a 

 little over a mile wide with a maximum 

 depth of about thirty feet and an average 

 of from ten to fifteen feet. The beach is 

 faintly but clearly marked to the foot of 

 Trout Lake and the shore mark of the river 

 in expanded portions and at some of its 

 rapids was found at several points below. 

 The best evidence of the existence of the 

 ancient river was found where it crosses 

 the course of a bouldery morainic deposit. 

 The boulders in such rapids were scoured 

 by the sand and pebbles moved along by 

 the current into peculiar forms readily rec- 

 ognized. These rapids were located at mo- 

 raine crossings. Others were less certainly 

 determined. The place of one cataract was 

 also found. In one of its rapids the ancient 

 river was between 600 and 700 feet wide, 

 with an average depth of 35 to 40 feet. 

 This corresponds very closely, in a general 

 way, with the size of the modern St. Clair 

 and Detroit rivers. The remains of the 

 ancient river agree with the Nipissing beach 

 in indicating that this arrangement of the 

 upper Great Lakes endured for a relatively 

 long period of time. 



The paper was preceded by a review of 

 the works of previous observers. In discus- 

 sion G. F. Wright remarked the interest 



all must feel in the establishment of this 

 thesis and G. K. Gilbert discussed its rela- 

 tions to Niagara Falls as a chronometer. 

 Increasing knowledge brings increasing 

 complexity. 



Moraines of Recession and their Significance in 



Glacial Theory. F. B. Taylor, Fort 



Wayne, Ind. 



A summary of facts presented last sum- 

 mer at Buffalo was first given regarding 

 moraines between Cincinnati and the Straits 

 of Mackinaw, there being 15 in all, whose 

 diflerences depend on the topography of the 

 land. The oscillations of the ice front and 

 the moraines is so regular in period that 

 ups and downs of the earth's surface cannot 

 be utilized in explaining them. We are 

 forced to refer to astronomical causes and 

 their effects on climate. Precession of the 

 equinoxes, modified by the revolution of the 

 apsides, was cited as the best cause, with 

 intervals of 21,000 years. This time seems 

 long, but it is corroborated by the large 

 amount of clay in the moraines. The ef- 

 fects of the precessions of the equinoxes 

 were analyzed. The oscillation was corrob- 

 orated by the relations of the boulder belts 

 in three moraines near Fort Wayne, Ind., 

 to the line of drainage apparently taken by 

 the river that drained the glacier. 



In discussion G. K. Gilbert emphasized 

 the interest of the ideas and spoke of them 

 as supplying, if true, the clue for the corre- 

 lation of the moraines in various regions. 

 Frank Leverett spoke of the importance of 

 the estimates of time and significance of the 

 boulder belts. G. F. Wright remarked that 

 moraines of recession with halts, still im- 

 plied forward movement of the rear ice con- 

 tinually during halts. Mr. Taylor, in reply 

 to the last speaker, described the moraines 

 as having steep outer slopes and gradual 

 slopes inward, which is only explicable by 

 an advance of ice up to a point and then its 

 accelerated retreat. Mr. Heilprin raised 



