82 
channel had been partly filled up with glacial drift. Dr. 
Andrews has made a series of very precise observations on 
the raised beaches of Lake Michigan, which show that the 
surrounding country rose out of “the glacial sea between 
5,000 and 7,500 years ago. Many rivers besides Niagara 
have made new channels in the glacial drift by which their 
old channels were choked up. 
15. Astronomical Proofs of the recent Close of the Glacial 
Period.—According to Lieut.-Colonel Drayson, in the Quart. 
Jour. Geol. Soc. for 1871, it would appear thas 15,000 years 
before Christ the Arctic circle came down to latitude 54° 35’ 
N., or to about the latitude of St. Bees and Whitby. The 
climate commencing about 21,000 years ago, would become 
more and more extreme up to about 15 ,000 years ago, and 
then gradually more and more equable to about 6,000 years 
ago. 
"16. Historical Objection to the recent Close of the Glacial 
Period.—Some notice ought to be taken of an objection to 
the recent termination of the olacial period made by Professor 
Bonney, on the ground that, if it came to aclose so late as 6,000: 
years ago, the climate would have continued down to 3, 000 
years ago sufficiently cold to excite the notice of historians. 
But, according to Colonel Drayson’s calculations, the climate 
would have lost its extreme character much earlier than 3,000 
years ago. It may likewise be remarked that glacial con- 
ditions in Britain never extended farther south than the 
Bristol Channel and Thames estuary, so that in countries 
farther south the climate 3,000 years ago may not have been 
sufficiently extreme to invest it with historical interest. 
THE CHArRMAN then said, I am sure all will be glad to hear the remarks. 
any one present might have to offer. 
Mr. E. Cuariesworty, F.G.S. (a Visitor).—Geological science is one of 
those branches of human investigation which, charming and attractive as it is 
to all who love the attempt to increase the boundaries of human knowledge, is 
nevertheless, one which I have felt, ever since I first took it up as a study, 
to be replete with uncertainties ; and of all the uncertainties that beset the 
geologist in his pursuits I think the one I should single out as par excellence 
the most perplexing, and the most unsatisfactory, is the attempt to measure 
geological time. Some of the greatest writers on the subject of geology have 
told us that there are evidences of life having existed on this planet countless 
years ago, and that, in point of fact, we can only gain an idea of geological 
time by comparing it with what we may term astronomical time. We know 
that we may penetrate millions of miles through space, and then be no 
nearer its confines than before. But when we are told by great authorities 
