1882.] 51 [Davis. 



structure, but of denudation; and the grooves on the surfaces of the rocks 

 which descend under their waters, appear to point to glacial action as one 

 of the great causes which have produced these depressions." (Geol. of 

 Canada, 1863, 889.) 



T. Belt follows Ramsay. (On the Formation and Preservation of Lakes 

 by Ice Action ; Geol. Soc. Journ., xx, 1864, 463-465.) 



The controversy between J. B. Jukes and H. Falconer in the Reader 

 (1864, 173, 269, etc.,) was whether valleys and lakes are the result of 

 erosion or dislocation ; Falconer holding to the old idea that general erosion 

 has played a small part and that glaciers have done nothing but occupy 

 basins to the exclusion of sediment ; Jukes claiming that more surface forms 

 depend on erosion than on construction, and that in the formation of lakes 

 glacial erosion is the " only mode of escape out of a great difficulty." He 

 elsewhere says that lakes were always a puzzle till Ramsay suggested their 

 true explanation. (Brit. Assoc. Rep., Address to Geol. Sect. 1862.) 



J. M. Wilson observes that erosion depends on joints, and thinks that if 

 the joint surfaces were concave, lake-basins would be formed as blocks of 

 rock were pushed away. (On the forms of valleys and lake-basins in Nor- 

 way, Geol. Mag., ix, 1872, 481-484.) 



A. Helland points to the moraines partly enclosing many Norwegian 

 lakes, and takes them as evidence that the basins were cut out by the 

 terminal part of the old glaciers. He insists that many of these lakes are 

 in true rock-basins and therefore must be due -to glacial excavation. 

 (Die glaciale Bildung der Fjorde und Alpenseen inNorwegen; Pogg. Ann., 

 CXLVi, 1872, 538-562.) 



J. S. Newberry describes the eastern Great Lakes as excavated from 

 solid rock once continuous over the area now occupied by water; the agents 

 of erosion were water and ice, ' ' and of the two that which was by far the 

 most potent and that which alone could excavate broad, boat-like basins, 

 such as these, was ice." (Geol. Ohio, 1873, I, 49.) " There can be no 

 doubt that the basin of each of the Great Lakes has been produced by a 

 local glacier," either before or after or before and after their occupation by 

 the continental glacier. (Geol. Ohio, n, 1874, 74. Professor Newberry's 

 latest paper on this subject has just been published in Amer. Phil. Soc. 

 Proc, xx, 1882, 91-95.) 



G. J. Hinde writes, " when the path of the glacier can be thus traced, 

 following the axis of the Lake (Ontario) from north-east to south-west, and 

 masses of till which have been eroded from the rocks outcropping in the area 

 of the lake are met with heaped up on the banks at its south-west end, the 

 only conclusion which can be drawn is that the lake-basin is due to the 

 powerful eroding influence of a glacier." (Canad. Journ., xv, 1877, 396.) 



N. S. Shaler says, " the lakes of Switzerland, those of New York and New 

 England, are good and familiar instances " of glacial erosion. " On a larger 



