282 Correspondence — Professor T. G. Bonney. 



COiaiaESIPOIiTIDIEJIl^CS. 



THE EIVER OF THE BALTIC. 

 Sir, — Mr. Hudleston's paper " On the Eastern Margin of the 

 North Atlantic Basin " is so full of important facts, and so carefully- 

 thought out, that I am almost afraid to criticize even a minor detail. 

 But in rejecting, with a note of sarcasm, the suggestion that the 

 deep channel which runs round the southern lobe of Norway may at 

 one time have carried off the drainage of the Baltic area (then land), 

 because the soundings go down to MO fathoms in the Skagerak, off 

 Arendal, and are not more than 160 fathoms in one part west of the 

 Naze, has he not overlooked some possibilities ? Obviously " the river 

 of the Baltic must have had some difficulty in draining towards the 

 Atlantic under these circumstances." But have " these circum- 

 stances " always existed ; in other words, are we entitled to assume 

 (as he has tacitly done) that the present slope of the bed is the 

 original one ? Apart from that, if the channel is not a portion of 

 an old river system — an ancient valley — what is it ? If it be made 

 by crust movements, the shape is singular, and we may fairly ask, 

 if called upon to put away our belief, for something better as 

 a substitute. Or would Mr. Hudleston allow it to be a valley, 

 but draining southward ? If so, what became of it, and is there 

 any evidence of a general drainage in that direction as tbe Pliocene 

 period was nearing its end ? If ever the bed of the Baltic became 

 dry land its drainage would have to go somewhere, and one or twa 

 North German rivers also would have to be accommodated. I am 

 aware that the second set of movements in the Alpine chain greatly 

 modified the drainage system of Europe, but I doubt whether there 

 have been any revolutionary changes since that epoch. Assuming 

 then, as I suppose we are justified in doing, this channel to be 

 a Pre-Glacial feature, are we warranted in also assuming its bed to 

 have retained its original slope and contours without any alteration ? 

 The present form is peculiar and suggestive. In Bohus Bay, almost 

 west of Lake Wettern, is a limited area in which the soundings reach 

 355 fathoms (a larger one being below the 250-fathom contour), and 

 in one place, slightly north of the latitude of Christiansand, we find 

 430 fathoms. The channel round the southern end of Norway (the 

 deeper part being on that side) seems to vary from 250 to 300 

 fathoms. Then (north-west of the Naze) it rises for a little while 

 to from 150 to 175 fathoms, and afterwards, till about opposite to the 

 Sogne Fjord, it barely reaches 200 fathoms. But then it steepens 

 Steadily till off the Komsdal Fjord, where it returns to 400 fathoms. 

 Doubtless this variation in depth is remarkable, but we must 

 remember that if the channel be Pre-Glacial much debris must 

 have been ' dumped ' irregularly on its floor, even though it proved 

 a barrier to the westward march of the Scandinavian ice-sheet. W© 

 must also remember that the Post-Glacial movements of recovery 

 in Norway have been very far from uniform. There is, how- 

 ever, another remarkable fact which appears to have escaped my 

 friend's notice. This basin of the Skagerak lies on the westward 



