730 report — 1884. 



south-eastern Salisbury comes out from beneath the dwindled, fiattened-out and 

 worn-off mountain synclinal. And the reason why this limestone is exposed to 

 view over plains miles in width, east and west of the Taconic Mountain, as well as 

 to the south, is simply this, that the once overlying schist has been removed because 

 in badly broken anticlinals and synclinals. 



The paper closed with an allusion to the orographic, stratigraphical and litho- 

 logical interest of the facts, and to their important bearing on the question of the 

 origin and chronology of certain kinds of crystalline rocks, such as chloritic, gar- 

 netiferous and staurolitic mica schists, as well as others less coarsely crystalline. 



7. Notice of a Geological Map of Monte Somma and Vesuvius. 

 'By H. J. Johnston-Lavis, M.I)., F.G.S. 



Vesuvius (using this term for the whole volcanic pile) is of all known volcanoes 

 that one which has been most studied and written about, its phenomena more 

 investigated than any of its rivals, and although its early history is not so complete 

 as that of its fellows, Etna and Stromboli, yet its eruptions during the Christian 

 Era are so intimately connected with the ill-fated cities of Pompeii, Sec, and thus 

 with archaeology, that this alone is sufficient to make it most prominent. 



But beyond this its geological structure is so varied, its products so numerous, 

 its past and present historic activity permitting the comparative study of these to 

 be carried on, together with its convenient size and accessibility, led the author 

 some years since to conceive the idea of minutely investigating its phenomena and 

 structure, which it is his intention to publish in the form of a monograph and a 

 geological map. 



The two out of six sheets forming the splendid map constructed in 1876, by the 

 students of the Italian School of Military Topography, on the large scale of 

 1 : 10,000, have been coloured in seven different tints, indicating the various 

 products of different eruptive periods l with indications of dykes, of lateral 

 craterlets, of springs simple, or thermo-mineral, blowing caverns, buried antiquities 

 ("of geological interest), &c. The work has now extended over four summers, and 

 the examination of about half, including the most complicated part of the mountain, 

 has-been completed, and the author hopes that if he is able to continue the work 

 during the present and next summer, to finish it by the autumn of 1885. This 

 long time occupied in the work is dependent on various causes. 1st. The great 

 intricacy of the geology. 2nd. The thick vegetation requiring very numerous 

 traverses. 3rd. The author, for professional reasons, being only able to devote the 

 summer months to the work, the hot Neapolitan sun of this season is so exhausting 

 that not more than four field days a week are possible, and even then at a considerable 

 sacrifice of health. In the two sheets exhibited are a few blanks that require 

 further study or have been left for various reasons. The work on the other four 

 sheets is of so scattered a nature at present that it was not thought advisable to 

 exhibit them till in a more complete state. 



Besides the actual mapping, a large amount of notes of a descriptive character 

 have been collected, and all the important features and sections photographed on a 

 large scale. Specimens of the various lavas, ejected blocks, tufas, pumices, &c, 

 have been carefully selected as the work went on, so that the author has now in 

 his possession by far the most complete geological collection from the mountain yet 

 extant, which is open to the study of anyone who should care to investigate its 

 contents. 



8. Report on the National Geological Surveys of Europe. — See Reports, 



p. 221. 



1 See Memoir by the author in Quarterly Journal of the Geological Society, 

 January 1884. 



