540 T. H. Holland — Roch-weathering and Seiyentinization. 



I imaj>-ine that tliese flats and terraces mark former levels of the 

 fjord. There is no evidence that either the Sandven Vand or Graven 

 Vand are rock basins, but in conclusion I will say a few words about 

 a lake which I am inclined to think is a rock basin, though I could 

 not prove this for certain without boring. I refer to the lake at 

 Noreimsund on the north side of the Hardanger Fjord. 



The outlet of the lake reminds one of the outlet of Loch Etive, 

 near Oban, but it is on a much smaller scale and is the best example 

 of its kind I have seen. The water flows over a rock-lip, the whole 

 of which from shore to shore is perfectly clear. At high-tide the 

 lake becomes, in fact, the end of the fjord, whereas at low - tide 

 a stream pours over the rock and forms a small catai'act. There is 

 one place, about a hundi'ed yards west of the outlet, where rock does 

 not show at the surface of the ground, and where there may possibly 

 be a buried channel passing to the fjord behind the village. In any 

 oase the locality is interesting and well worth a visit. 



III. — A Contribution to the Discussion on Eock - weathhi{ing 



AND SeRPENTINIZATION. 

 By T. H. Holland, Officiating Superintetideut, Geological Survey of India. 



BY correlating the head and the tail of Professor G. P. Merrill's 

 "Discussion on the use of the terms Eock- weathering, 

 Serpentinization, and Hydroraetaraorphism," ^ I infer a direct 

 invitation to confer with him on the questions raised by me at 

 the Bristol meeting of the British Association. - 



At the outset it should be explained that, though not so apparent 

 from the published abstract, reference to the full text of my paper 

 as read shows that Professor Merrill and I have on many points 

 independently arrived at similar conclusions. 



In his " Treatise on Eocks and Eock - weatheiing," Professor 

 3Ierrill called attention to the not nnfrequent omission in geological 

 literature of a precise distinction between the Avork of subaerial 

 agents and the deep-seated forms of hydrometamorphism and 

 alteration. But although he included " epidote, chlorite, sericite, 

 leucoxene, kaolin (?), pyrite, and various zeolitic compounds " in the 

 latter category, he made no mention of serpentine. Professor 

 Merrill says that the distinction drawn by him in 1897 between 

 weathering and the more deep-seated alteration of rocks is 

 essentially that made by Eoth between Venoitleriing and compHcirte 

 Venmtterung.^ He also now says that whilst Eoth in 1869 spoke of 

 serpentine and zeolites as products of weathering (Verioitterung) , 

 he so far changed his views or mode of expressing them in his 

 latest work (1893) as to call the deep-seated process complicirte 

 Verwitterung in distinction from the purely superficial Verwiiterung 

 due to atmospheric action. 



^ Geol. Mag., August, 1899, pp. 354-8. 



- " The Comparative Actions of Subaerial and Submarine Agents iu Eock Decom- 

 position " : Rep. Brit. Assoc, 1898, p. 868; Geol. Mag., January, 1899, p. 30. 

 ^ " Rocks and Rock- weathering," pp. 161 and 174 (footnote). 



