SOME EVIDEVCKS OK A GLACIAL EPOCH. 



for the ice Ago, it entered Lake On- 

 tario at its western extremity at the 

 pcint where Hamilton now stands. 



The calculations as to the length of 

 time since the Glacial Period, are 

 based upon the wearing- away of the 

 rock at the Falls of Niagara. The 

 yearly loss of rock by denudation is, 

 roughly speaking, some three or four 

 feet, or even more, as it does not wear 

 evenly, hence its horseshoe 'form. 

 Take this length and divide into the 

 length of the gorge, and we have a 

 quotient giving from 8,000 to 10,000 

 years as the age of the river, in other 

 words, as the river is an outcome of 

 the Ice Age, it must be that length of 

 time since the glaciers disappeared 

 from the Niagara district. Undoubt- 

 edly we must assume in this case that 

 the same continuity of the volume of 

 water has existed since the Glacial 

 Age. 



In the upper part of the Mississippi 

 River is another post-glacial gorge, 

 which forms a valuable indicator as 

 to the time of the Glacial Age. The 

 results here about coincide with those 

 arrived at with regard to Niagara. 

 Other similar cases of denudation give 

 approximately the same results. 



The silting up of lakes, whose beds 

 were formed by the agency of ice, 

 show that the Glacial Era could not 

 have been much more remote. 



Take your own lakes near St. John, 

 which are all of glacial origin. They 

 are small, and receive a quantity of 

 mineral and organic matter, brought 

 down from the hills by the various 

 streams, and deposited in them, by 

 which means they gradually become 

 filled up. Both Lily and Ashburn 

 lakes have already become nearly 

 filled with silt, in their shallower por- 

 tions. In a comparatively short time, 

 geologically speaking, both will be- 

 come swamps, while only a little 

 while afterwards they will be flat 

 grass-land, just as the old rifle-range 

 land now is. That ground was un- 

 doubtedly a lake at one time, but be- 

 came filled up with mineral and or- 



ganic matter, brought down by the 

 streams from the hills around. 



You may ask, "What has this to do 

 with the Glacial Age?" Well, simply 

 this : A computation of the amount of 

 silt there is in the lake, before the 

 hard rock-bed is reached, will give 

 the age of the lake, if the average 

 yearly deposit can be obtained. Cal- 

 culations based upon such data, ap- 

 liroach very nearly in results to those 

 deduced from the erosion of rivers. 



It is a moot point amongst geologists 

 v/hether the age we are now speaking 

 of, was really a time when whole con- 

 tinents were under glacial ice, or 

 whether local climatic influences, 

 ccupled with changes of land eleva- 

 tion, would be sufficient to produce 

 this phenomenon. Further, Sir Wil- 

 liam Dawson has shown that a species 

 of Drift Deposit Is being accumulated 

 at the present time in some of the 

 openings of the Canadian Coast, this 

 deposit being formed by the agency 

 of floating ice, in the shape of either 

 bergs or drift-ice. Moreover, the 

 rocks are often much striated. It 

 will be well to remember the fact here, 

 that an iceberg has only about an 

 eighth of its entire mass above the 

 water, the rest being submerged. You 

 can imagine at what a depth some 

 would be in the water, when I mention 

 that I have, myself, seen icebergs some 

 200 feet high, in and near the Straits 

 of Belleisle. So soon as such a mass 

 of ice gets into comparatively shallow 

 v/ater even, it would run aground, and 

 be swaj'ed about by either the wind 

 or current, In some particular direc- 

 tion, when any stones sticking under- 

 neath would be scraped across the 

 sea-floor, by which means they would 

 become striated. Notwithstanding 

 the proofs that in particular instances 

 floating ice may lay down Drift Beds, 

 the consensus of opinion shows that 

 such a deposit as the one particularly 

 described tonight, must have been laid 

 down by glacial action, and for the 

 reasons already mentioned, but which 

 it might be well now to recapitulate. 



