Br. H. Landor — On Ground-ice as a Carrier. 461 



more difficult of compreliension. If, tlien, this is not so, as it seems 

 to me impossible it should be, the reason why ground-ice forms is 

 not because the water is all below 32"^, and the bottom of the river 

 colder still to make the ice adhere to it. I never tried the temperature 

 of the bottom, for it is a problem too difficult for practical solution 

 (without much care and expensive apparatus) to find the tempera- 

 ture of the stones while they are in situ. No doubt there is wanting 

 a well-conducted series of observations of the temperature of the 

 river and bottom, night and day, which it has never been in my 

 power to make. It seems to me, from theory, that the stones must 

 be below 32°, and it is to me utterly impossible to say how they 

 become so in such a situation as they are. Any scientific work on 

 temperatures will give various theories on this subject, so that I 

 need not take up time in alluding to them. None of them, to m}' 

 mind, fulfil all conditions ; and, if it were only for this object, 

 further observations are desirable. 



" I will pass on to the results of ground-ice, and first on the 

 subject of stones and boulders. If on one river so many stones as 

 I have seen go down the Thames are carried, some of them as far as 

 Lake Erie, what must be the amount on all the rivers emptying 

 into the lakes ? The stones are for the most part portions of those 

 contained in the glacial drift, which covers so large a part of Canada, 

 and they have already been brought to the beds of the rivers from 

 distant sources ages ago, in the glacial period. This removal by 

 ground-ice is, therefore, their second journey. Now, suppose that 

 Lake Erie were laid dry, its surface would present the appearance 

 of a level plain, covered more or less with pebbles and boulders of 

 the same kind of stones as those contained in the glacial drift on 

 the rest of Canada. Would not any geologist, unacquainted with 

 the phenomena of ground-ice, say that the stone-covered plain of 

 Erie was the result of glacial times also ? But how wrong he would 

 be. For it would owe its boulders and pebbles to the action of 

 causes ages subsequent to the glacial period. So far from the pebbly 

 drifts being contemporaneous with the drift of the present dry land 

 of Canada, it would belong to distant geological epochs, widely 

 apart in time, and wider still in climate. How difficult it is in 

 geology to say what deposits are contemporaneous, or what sepa- 

 rated by ages. In this case the fauna might enable the geologist to 

 discriminate if any should be deposited. All the stones he would 

 see might, and most probably would have been brought by ground- 

 ice. Suppose that one river only takes 10 stones a winter into 

 Lake Erie, a ridiculously low estimate. There are above 80 rivers 

 debouching into Lake Erie, not counting those that come laden with 

 stones by means of the Detroit river, probably equalling in results 

 all the 80 put together. That would give 1,600 stones in one winter. 

 Now, according to Lyell, 30,000 years have passed since Erie and 

 Ontario bore their present form, which in that time gives 48 million 

 of stones, and this is a most moderate estimate of the result in both 

 time and quantity. I give it to show that the effect of ground-ice 

 during incalculable ages must be important, and the cause of con- 



