Yol. 69.] AGE OF THE SUFFOLK VALLEYS. 611 



not yet know, however, whether a depth of over 400 feet (as at 

 Glemsford) could be excavated by sub-glacial water. 



The presence of these channels helps to prove that the valley- 

 system of to-day is older than the valley-glaciers which appear 

 to have formed such deep hollows. It is interesting in this con- 

 nexion to note that Dr. Emil Werth and others describe in detail 

 similar channels due to the excavating action of sub-glacial water- 

 streams which bubble up and emerge at the snout of the glacier. 1 

 These are termed Fohrden or Forden in Sehleswig-Holstein, 

 Fjarde in Sweden, and Fjorde in Denmark (not to be confused 

 with fiords). The characteristics of these Fohrden are their 

 parallel or radiating arrangement; their long narrow form; their 

 perpendicularity to the ice-edge and to the terminal moraine; their 

 association with deposits of morainic character; the existence of a 

 threshold or sill between them and the sea; and their occurrence 

 on a recently-glaciated, comparatively-low country bordering the 

 sea. 2 Besides their distribution as noted above, they have been 

 studied in Kerguelen by the German Antarctic Expedition of 

 1901-1903. 3 



The occurrence of deep channels filled with Drift in Suffolk 

 valleys, associated generally with mounds of glacial debris, 

 morainic or glacieluvial gravels, and great masses of Boulder Clay, 

 as well as with intense glacial disturbance, is certainly significant, 

 and is worthy of further attention. It does not seem improbable 

 that here we may have hollows analogous to the true Fohrden, 

 described so graphically and in so much detail by Dr. Werth 

 (indeed, paragraphs from the latter' s pen apply equally well to 

 Suffolk conditions). 4 



Dr. Werth, in a letter, tells me that he knows of no examples 

 in North Germany filled entirely with Glacial Drift, but that the 

 complete filling-in of Suffolk channels may be due to the fact that 

 they belong to an older glaciation. Mr. F. W. Harmer has 

 expressed the view that the ' Cannon-Shot ' Gravels of Norfolk, 

 with their spherical flints, may be due to the action of sub-glacial 

 water-streams, 



VI. Theoeetical Questions and General Bemarks. 



Sir J. B. Phear noted in 1856 that the Gipping was a dip- 

 stream flowing south-eastwards from the Chalk escarpment, which 

 runs generally from south-west to north-east, and examination of 



i These ' submarine wells ' of fresh water emerging as fountains in the 

 Greenland fjords were noted as far back as 1877 by Henry Kink (' Danish 

 Greenland : its Peoples & its Products ' London, 1877, pp. 50, 360-63). Such 

 fountains of fresh water burst out with great violence on a sudden fall in the 

 level of marginal lakes of the Greenland ice-sheet. See also W. H. Hobbs, 

 1911 (30) up. 175 et seqq. 



2 Werth, 1909 (26, 27, 28) & 1912 (36), 



3 Id. 1908 (24) pp. 130-48. 



4 For references to further work on Fohrden, see the authors quoted in 

 Werth, 1908 (24) & 1912 (36), as also K Olbricht, ' Die Esarationslandschaft ' 

 Geol. Eundschau, vol. i (1910) p. 59 and references there. 



