638 SCIENCE PROGRESS 



(Proc. Amer. Acad. Arts and Sciences, November 191 5). Instead 

 of crustal subsidence, a rise of sea level, due to the restoration 

 of water previously locked up in the great Pleistocene ice-sheets, 

 is invoked to explain the observed phenomena. The platforms 

 of uniform depth upon which the reefs grow are supposed to 

 have been formed by wave action during the preceding cold, 

 rough period of general lowering of the ocean level. 



The phenomena of the repose periods of Vesuvius, Etna, 

 Stromboli, and Vulcano have been described in an interesting 

 paper by H. S. Washington and A. L. Day {Bull. Geol. Soc. 

 Amer. 1915, 26, 375). This study was incidental to a larger 

 investigation, now proceeding, of the gases, salts, and rocks 

 collected from these volcanoes, with a view to determining 

 the composition of the magmatic gases, their possible exothermic 

 interreactions, and correspondence with the general chemical 

 characters of the erupted rocks. A further object was to 

 confirm the presence of water in the unaltered volcanic gases, 

 as has already been done in the Hawaiian volcanoes, in refu- 

 tation of Brun's recent hypothesis of the anhydricity of vol- 

 canic action. 



The Summary of Progress of the Geological Survey of Great 

 Britain for 1914 (191 5) briefly records the work done in many 

 parts of the country. A volcanic phenomenon of great interest 

 is described from Mull as the remains of a great caldera, with 

 thick marginal breccias, and an internal series of lava-flows 

 2,000 to 3,000 feet in thickness, which frequently exhibit 

 pillow-structures. This is believed to indicate the former 

 existence of a lake in the caldera ; but recent work by Lewis 

 has shown that it is no longer necessary to postulate extrusion 

 into or under water in order to explain pillow-structure. Re- 

 markable vertical intrusions of circular outline, described as 

 ring-bosses or ring-dykes, are believed to have arisen along 

 faults bounding circular subsidences, similar to the well-known 

 cauldron subsidences of Glen Coe and Ben Nevis. 



Stratigraphical and Regional Geology. — The debated question 

 of the relative ages of the Moine Gneiss and Torridon Sandstone 

 of the Scottish Highlands has been advanced a stage by Prof. 

 J. W. Gregory's discovery of pebbles of rocks indistinguish- 

 able from typical Moine gneisses in the Torridonian conglomerate 

 of Little Loch Broom (Geol. Mag. October 1915). The identi- 

 fication is supported by Dr. J. J. H. Teall and Dr. J. Home. 



