*;186 Geological Society : — 



dykes of dolerite ; granites ; clay-slates, sandstones, and schists, 

 with copper, lead, and tin ; limestones, serpentines, and hornblendic 

 rocks, with talc, steatite, etc. ; various schists, quartzites, and lime- 

 stones. The summary of the author's observations leads him to 



* suppose that there are at least three distinct limestone or. calcareous series 

 in Kumaon and Garhwal, and that schists and quartzites, with several isolated 

 patches of granitic rock, form a large part of the remaining formations/ 



3. ' Tin and Tourmaline.' By Donald A. MacAlister, Esq.,F.G.S. 



Cassiterite hardly ever occurs without tourmaline, though the 

 latter is found without the former : hence it appears that tourmaline- 

 producing constituents and influences are of wider range than are 

 those of cassiterite. Boron-trioxide is an extremely common accom- 

 paniment of volcanic action, and there can be no doubt that it has 

 acted powerfully in changing such original minerals as the micaceous 

 and felspathic ingredients of crystalline rocks. Prom a comparison 

 of formulas representing tourmaline and felspar, it is evident that 

 the act of tourmalinization has been accompanied by a loss of soda. 

 The excess of this soda will combine with boric acid, forming niefa- 

 borate and pyroborate of soda. The former, acting on disseminated 

 tin-ore. might result in the production of sodium-metastannate and 

 borax. The metastannate is soluble, and capable of being leached 

 out of the magma, and, by a new reaction, tin-oxide may be 

 precipitated and concentrated, while sodium-metaborate may be 

 liberated. According to the cooling-curve of solutions, in all pro- 

 bability deposition of the oxide of tin would take place more 

 rapidly at a certain stage in the process of cooling than at others. 



December 3rd.— Prof. Charles Lapworth, LL.D., F.RS., 

 President, in the Chair. 



The following communications were read : — 



1. ' On some AVell-seetions in Suffolk.' Bv AVilliam Whitaker, 

 Esq., B.A., F.R.S., F.G.S. 



Xotes of thirty-one new wells have accumulated since 1895, some 

 of them giving results which could not have been expected. A trial- 

 boring for the Woodbridge Waterworks Company gave a depth of 

 133-^f feet down to Eocene beds, and a thickness of Crag about double of 

 any before observed in the neighbourhood. An analysis of the saline, 

 hard, water yielded is given. Three explanations are suggested : 

 a channel, a huge ' pipe ' in the Chalk, or a disturbance such as a 

 fault or a landslip ; but the author is not satisfied with any of them. 

 Two borings at Lowestoft show that Crag extends to a depth of 

 240 feet in one case, and over 200 feet in another : confirming 

 estimates of Mr. Harmer and Mr. Clement Eeid. In one of these, 

 Chalk was reached at 475 feet. Three other wells in the neigh- 

 bourhood confirm the great depth of the newer Tertiary strata. 

 Sections are also given from the following places : — Boulge, 



