Correspondence — Prof. John Milne. 427 



tlie action of coast-ice on a rising area has produced many pheno- 

 mena which are inexplicable by the action of continental glaciers. 

 On the other hand, Dr. Linnarsson shows that there are phenomena 

 which I did not even refer to in my paper that may have been pro- 

 duced by a continental sheet of ice, but not by coast-ice. 



To all this I see no objection, and so long as Dr. Linnarsson only 

 claims a reasonable proportion of the so-called glacial phenomena as 

 the result of the action of his continental sheet, I shall be content 

 to see the leavings sifted and a certain proportion of them set down 

 to the credit of coast-ice acting on a rising area. 



So much then for the general argument embraced in Dr. Linnars- 

 son's communication. I will now turn to one or two of his details. 



First, I cannot agree with Dr. Linnarsson that the scratches pro- 

 duced by coast-ice are " independent of the slope of the land." In 

 making this statement, it appears to me that he has apparently 

 omitted to notice the most effective of the methods in which coast- 

 ice acts. Looking at a coast-line generally, the slope of the land 

 will be at right angles to its direction, and the scratchings and 

 furrowings due to the action of ice being produced by the driving 

 in or " raftering " of the pack-ice upon the ice-foot or " balacada," 

 the markings which are produced must be parallel to this move- 

 ment, that is, at right angles to the shore-line. If, on the other 

 hand, the " currents and winds " are very oblique or parallel to the 

 coast-line, the balacada will usually remain unmoved, and will only 

 be chafed as the pack-ice floats along its outer edge, or what the 

 inhabitants of Labrador and Newfoundland call the "drain." 



If we consider the way in which scratchings are produced by the 

 dragging and sliding of coast-ice back towards the sea, and say 

 the markings which will remain behind are independent of the slope 

 of the land, we shall next, perhaps, be induced to say that the 

 direction in which rain runs from the roof of a house is also inde- 

 pendent of the direction of its greatest slope. 



At the commencement of Dr. Linnarsson's letter, when speaking 

 of my arguments, he says, " I think that most of your readers do 

 not need to have the failings of such reasonings pointed out." The 

 reasons here referred to are my arguments in reference to the action of 

 coast-ice. "What must the readers of the Geological Magazine think 

 of the authoritative statements and arguments of Dr. Linnarsson, 

 when they read at the termination of his letter that " The rocks (on 

 the coasts of Sweden and Finland) are there so hard and compact, 

 and the force of the waves so small, that their action on the rock 

 surface is hardly perceptible. A rock may be exposed there for 

 hundreds of years to the waves without the finest scratches being 

 abraded." Whilst remembering that a rock exposed to the waves 

 must also be exposed to the atmosphere, six lines further on they 

 then read that, "In the open air the scratches usually become 

 obliterated in a few years," etc. ? 



All this is brought forward, I may mention, in opposition to an 

 opinion I expressed that all glaciated rocks, in order that their 

 scratched surfaces may retain their character, "must always have 



