226 Prof. S. H. Reynolds — Serpputine near Wells, Somerset, 



South Wales, to Devon and Cornwall, and which is generally 

 attributed to the work of the Pliocene sea.' The suggestion is 

 therefore made that the picritic serpentine is derived from a boulder 

 dropped from an iceberg floating in the Pliocene sea. 



Dr. J. S. Flett's description of the specimens sent to Mr. H. B. 

 Woodward by Mr. Balch is as follows : — 



" Augite Picrite, passing into serpentine." 



" The hand specimens have a dark green colour and a smooth 

 fracture, with slightly unctuous feel. The microscopic section shows 

 that the rock consists mostly of roimded grains of olivine, decom- 

 posing into aggregates of yellow and green serjDentine. These are 

 partly embedded in or surrounded by irregular plates of pale brown 

 augite, evidently of later formation than the olivine, on which it 

 is to some extent moulded. Olivine forms at least one-half of the 

 rock, and hence typical lustre inottling is not developed. A little 

 secondary hornblende is also present. In all its features this rock 

 is identical with the picrite of Clicker Tor, Menheniot, ConiAvall, 

 from which it has probably been derived." 



The silica ]iercentage as determined by Mr. E. M. Lane in 1906 

 in the chemical laboratory of University College, Bristol, is 30"66. 

 The specific gravity as determined both by Mr. E. M. Lane and 

 Mr. F. S. Wallis is 2"71, the relative lowness being no doubt 

 attributable to the weathered character of the rock. 



1 Soe Barrow, Quarl". .Joiirn. Geol. Soc, vol. Ixiv, 1908, p. 384. , 



