Geological Society of London. 429 



which rises from deep water on either side to within a thousand 

 fathoms of the surface of the sea. The general direction of the ridge 

 is N.N.E. and S.S.W. 



(1) A line of volcanoes, some active, some extinct, traverses the 

 group. Continued southward, the direction of the line passes through 

 the volcanoes of the Eermadec group, and those of the Taupo zone 

 of New Zealand ; while to the north it cuts the line of the Samoan 

 volcanoes at right angles. 



(2) Besides the purely volcanic islands there are some formed by 

 submarine eruptions, whose layers have been laid out under water 

 and since elevated, with or without a covering of limestone. 



(3) The remaining islands ai'e formed entirely of limestone. 



Eua is an example of the second group. The volcanic basis con- 

 sists for the most part of beds laid out beneath the sea, and some of 

 the upper ones contain pelagic shells. Dykes of augite and hyper- 

 sthene-andesite project on the shore, and a representative of the 

 plutonic series occurs. There is evidence that the island has been 

 elevated and again submerged prior to the elevation which has raised 

 it to the present height. The volcanic basis is largely invested with 

 limestone, and this rock forms the summit 1078 feet above sea-level. 

 Sections show that it is a shallow-water deposit. 



Of the purely limestone structures, Tongatabu, Nomuka, and the 

 long reef on which the larger islands of the Hapaii group are 

 situated, form more or less complete atolls, all of which have been 

 elevated to a greater or lesser extent. 



The Vavau group is remarkable for its very indented contour, 

 suggesting the idea that it rests on a much denuded basis. Both 

 here and at Eua there are raised limestone formations with atoll or 

 barrier-like contours ; and there is some direct evidence to show 

 that these have been formed without the aid of subsidence. 



The presence of islands formed of volcanic materials laid out in 

 layers beneath the sea, and the manner in which the recently formed 

 Falcon Island is now being reduced to the condition of a submarine 

 bank, suggests that the atolls of the group may rest on similarly 

 formed foundations. 



4. "On the Inverness Earthquakes of November 15th to De- 

 cember 14th, 1890." By C. Davison, Esq., M.A. (Communicated 

 by Prof Charles Lapworth, LL.D., F.E.S., F.G.S.) 



In this paper the author gives reasons for supposing that the 

 Inverness earthquakes of last year were due to the subsidence of a 

 great wedge of rock included between a main fault and a branch 

 one ; and he considers that there is little doubt that these recent 

 earthquakes were the transitory records of changes that, by almost 

 indefinite repetition in long past times, have resulted in the great 

 Highland faults. 



The next meeting of the Society will be held on Wednesday, 

 November 11th, 1891. 



