Correspondence — C. D. Sherborne, A. J. Jukes-Browne. 331 



abundant as to constitute a rock-forming mineral, whilst as an 

 accessory it occurs also in the glaucophane-schist. 



The author further describes a peculiar epidote, containing iron, 

 from the glaucophane-schist, and also a peculiar garnet, occurring in. 

 rhombic dodecahedra about the size of a pea, which includes many 

 other minerals, but no glaucophane. The garnet is of a deep yellow 

 colour, and is anisotropic, a circumstance probably due to strain from 

 the interposition of other minerals. 



coiei^ESiPOD^nDiEin^rGiE:. 



NORWEGIAN "EHOMBEjST-PORPHYE" FROM THE CROMER 

 BOULDER-DRIFT. 



Sir, — In 1884 I collected some erratics from the cliff-sections 

 near East Eunton, amongst which was a specimen which proves to 

 be exactly similar to the well-known " Khomben-Porphyr " of 

 Southern Norway and elsewhere. It will be interesting, perhaps, 

 to put on record the occurrence of this uncommon and local rock. 

 A small piece of this specimen has been sent to the Mineral 

 Department, British Museum (Natural History). 



540, King's Road, London, S.W. Chas. D. Sherbobnb. 



THE GLACIAL DEPOSITS OF SUDBURY. 



SiE, — As one of those who believe that sea-ice was the main agent 

 in the formation of the East Anglian Drifts, allow me to enter a 

 protest against the conclusions drawn by Mr. J. E. Marr in his paper 

 on the Sudbury sections in the June Number of this Magazine. 



He entirely omits to consider the action of coast-ice on a sinking 

 shore, though he must be well aware that this agency has been 

 prominently referred to as concerned in the formation of Boulder- 

 clay. 



He asks the question, "Why are not the incoherent Tertiary beds, 

 on which the contorted Glacial deposits rest, themselves disturbed? " 

 and he thinks that this fact is incapable of explanation except by the 

 theory which invokes the passage of land-ice over the East of 

 England. I perfectly agree with him on the point that the incoherent 

 Tertiary beds could only escape contortion by being frozen hard so as 

 to behave like the harder rocks of other districts ; but is it, I would 

 ask, only on an actual land surface that such sands could be frozen 

 into a solid mass ? I am writing in the country away from books of 

 reference, but think I am correct in saying that the sand on the 

 shores of Siberia is frozen into a perfectly hard and solid mass for 

 some distance below the water, and I think the fact is mentioned in 

 Nordenskiold's " Voyage of the Vega." 



Mr. Marr dismisses the agency of icebergs because he thinks the 

 deposits could not be frozen " over large areas at the bottom of the 

 muddy sea in which the icebergs were drifted ; " this is probably 

 true of those parts of such seas in which large and massive icebergs 



