/. W. Judd — On Volcanos. 



59 



was to fully establish the presence of a central mass of basalt in the 

 midst of the hill ; the presence of which had been affirmed by " the 

 Yulcanists," and denied by "the Neptunians." From the results of 

 these workings we are enabled to give the accompanying section of 

 the Kammerbiihl, Fig. 3. 



Fig. 3. — Section of the Kammerbuhl in Bohemia. 



a, a. MetamorpMc rocks. 



b, Basaltic scoriae. 



c, Solid mass of basalt rising through the centre of the volcanic pile. 



d, d. Lava stream composed of the same rock. 



e, e. Alluvial matter surrounding the old volcano. 



N.B.— The dotted lines indicate the probable former outline of the volcano. 



English readers will doubtless call to mind that a similar experi- 

 mental test was at an earlier date suggested by Hutton, in the case 

 of the veins of the Salisbury Crags, and was carried out by his 

 friend Sir James Hall. 



We have been led to dwell at some length on this story of the 

 Kammerbiihl, because that object forms such an interesting and 

 instructive link between the undoubtedly extinct volcanos and the 

 so-called masses of "trap-rock." All through Northern Bohemia, 

 as well as in the districts of Silesia lying to the east, and in those 

 of Bavaria to the west, isolated masses of basalt, like that occujDying 

 the centre of the Kammerbiihl, occur by hundreds ; and the same 

 is found to be the case in the districts of Central G-ermany lying 

 between the Thuringerwald and Hartz Mountains on the east, and 

 the Ehine on the west. In many cases, as near Eisenach and Fulda, 

 such masses of basalt are shown by quarrying operations to be truly 

 intrusive, and are seen to have given off veins into and metamor- 

 phosed the surrounding rocks. Very interesting details concerning 

 the physical and petrological features of some of these old volcanic 

 ducts have recently been given by Prof. Mohl of Cassel. 



If districts, like those of the Auvergne or the Eifel, which exhibit 

 great numbers of small volcanic cones, were subjected to such an 

 amount of denudation as would remove the sheets of lava and the piles 

 of scorige, no trace would be left of the sporadic outbursts of igneous 

 forces, but a number of isolated masses of basalt or other igneous 

 rock, rising through the surrounding strata. Can we then doubt that 

 areas (such as those we have above referred to) which present 

 precisely these appearances were once surmounted by scattered 



