Date of the Glacial and the Upper Miocene Period. 369 



do so ; but in such a case the berg could produce but little effect 

 on the rock. 



Dr. Sutherland, who has had good opportunities to witness the 

 effects of icebergs, makes some most judicious remarks on the 

 subject. " It will be well, " he says, " to bear in mind that when 

 an iceberg touches the ground, if that ground be hard and resisting, 

 it must come to a stand, and, the propelling power continuing, a 

 slight leaning over in the water, or yielding motion of the whole 

 mass, may compensate readily for being so suddenly arrested. 

 If, however, the ground be soft, so as not to arrest the motion 

 of the iceberg at once, a moraine will be the result ; but the 

 moraine thus raised will tend to bring it to a stand "*. 



There is another cause referred to by Professor Dana, which, 

 to a great extent, must prevent the iceberg from having an op- 

 portunity of striating the sea-bottom, even though it were other- 

 wise well adapted for so doing. It is this : the bed of the ocean 

 in the track of icebergs must be pretty much covered with stones 

 and rubbish dropped from the melting bergs. And this mass of 

 rubbish will tend to protect the rockf. 



If icebergs cannot be shown a priori, from mechanical consi- 

 derations, to be well adapted for striating the sea-bottom, one 

 would naturally expect, from the confident way in which it is 

 asserted that they are so adapted, that the fact has been at least 

 established by actual observation. But, strange as it may ap- 

 pear, we seem to have little or no proof that icebergs actually 

 striate the bed of the ocean. This can be proved from the di- 

 rect testimony of the advocates of the iceberg theory themselves. 



We shall take the testimony of Mr. Campbell, the author of 

 two well-known works in defence of the iceberg theory, viz. 

 ? Frost and Fire' and 'A Short American Tramp/ Mr. Camp- 

 bell went in the fall of the year 1864 to the coast of Labrador, 

 the Straits of Belle Isle, and the Gulf of St. Lawrence, for the 

 express purpose of witnessing the effects of icebergs, and testing 

 the theory which he had formed, that the ice-markings of the 

 glacial epoch were caused by floating ice and not by land-ice, as 

 is now generally believed. 



The following is the result of his observations on the coast of 

 Labrador. 



Hanly Harbour, Strait of Belle Isle :— " The water is 37° F. 

 in July. ... As fast as one island of ice grounds and bursts, an- 

 other takes its place ; and in winter the whole strait is blocked 

 up by a mass which swings bodily up and down, grating along 

 the bottom at all depths. . . . Examined_the beaches and rocks 

 at the water-line, especially in sounds. Found the rocks ground 



* Quart. Journ. Geol. Soc. vol. ix. p. 306. 

 t Dana's ' Manual of Geology/ p. 677- 

 Phil. Mag. S.4. Vol. 36. No. 244. Nov. 1868. 2 B 



