730 



nEPOBT — 1884. 



i.ii-'' 



pouth-eastovn Salisbury comes out from beneath tlio tlwindU'd, flattened-out and 

 worn-oli' mountain synclinal. And the reason why this lirat'stonc 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 onc(> overlying- schist has been removed because 

 in badly brolten anticlinals and synclinals. 



The paper closed with an allusion to the orofjrajjhic, st rat igraph leal and htlin- 

 loprirnl interest of the facts, and to their important hearinfr on the question of tlio 

 orifrin and chronoloii:y of certain kinds of crystalline rocks, such as chloritic, trar- 

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



7. Notice of a Geological Map nf Monti; Somma fi)id Vexnrlus, 

 'ill/ H. J. Johnstox-Lavis, M.D., F.G.S. 



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

 that one which has been most studied and written about, its ])henoniena more 

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

 as that of its fellows, J']tna and Stnnnboli, yet its erupt i<in.s during the Chri.-tiiui 

 Kra art> so intimately connected with the ill-fated cities of I'ompeii, Sec, and thiw 

 with archajology, that this alone is siiilicient to make it most prcmiinent. 



But bej'ond this its geological structure is so varied, its ])roducts so inunerous, 

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

 be carried on, together with its convenient si/e and accessibility, led the author 

 some years since to conceive the idea of minutely investigating its ])henoinena 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 sjdendid map constructed in 1870, by tlic 

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

 I : 10,000, have been coloured in seven diiferent tints, indicating the various 

 products of diflerent eruptive periods ^ with indications of dykes, of lateral 

 craterlets, of springs simjile, or thermo-niineral, blowing caverns, bm'ied antiquities 

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

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

 has been com])leted, and the author hopes that if he is able to continue the work 

 dui'ing 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. 2!id. The thick vegetation requiring very numerous 

 traverses, ilvd. 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 considerahle 

 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 cliaraoter 

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

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

 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 it^ 

 contents. 



8. Report on the National Gcoloijical Surveys of Eiiropr.—^ee Report? 



p. 221. 



' See Memoir by the author in Qtart-rly Journal of the (icohgical Sodei^j, 

 January 1884. 



