J". W. Judd — On Volcanos. 205 



charms. The artist and lover of picturesque scenery is attracted by 

 the remarkable contrasts afforded by the dark rugged igneous masses,. 

 surrounded by spires and precipices of glittering dolomite ; the 

 botanist finds a wonderfully varied flora growing upon its strangely 

 diversified soils ; the mineralogist recognizes it as an almost unri- 

 valled locality for many beautiful crystallized forms ; the palaeontolo- 

 gist knows of no richer hunting grounds than the beds of St. Cassian ; 

 the granites and porphyries of the area are among the best-known 

 types of the petrologist ; and the physical geologist has learnt 

 to regard it, ever since the days of von Buch, as a field in which a 

 solution of some of the grandest problems of his science may be hope- 

 fully sought. Few districts of equal area can, perhaps, boast of a 

 scientific literature so prolific ; and a list of works relating to its 

 geology alone, which was drawn up by Eichthofen in 1858, and 

 extends to ten quarto pages, would have to be very largely added to, 

 in order to bring it up to date. The visitors' books of the little inns in 

 the secluded valleys of the Southern Tyrol are collections of the auto- 

 graphs of scientific investigators ; and nowhere perhaps in the whole 

 world do the quiet and unobtrusive labours of men of science attract 

 so large an amount of popular attention as in these remote valleys. 

 The English geologist smiles to see in such a spot the portrait of 

 Sir Roderick Murchison, of course well be-starred and be-ribboned, 

 paired with that of Alexander Yon Humboldt, and both placed as 

 supporters to the picture of an Austrian Archduke, whose name was 

 given to a well-known mineral species. So great is the interest 

 excited by the remarkable rocks of this district, and especially by 

 those of Monzoni and Predazzo, and so various at the same time are 

 the conclusions at which different students of them have arrived, that 

 we may well call this region " the battle-ground of Petrologists." 



There are a number of different centres of eruption which can be 

 traced by an attentive study of the Triassic rocks of the Southern 

 Tyrol. jProm most of these great quantities of agglomerates, tuffs 

 and ashes were ejected, which have formed immense deposits in the 

 midst of the Triassic series, and from most of them lava either of the 

 type of augite-porphyry or melaphyre also flowed. Two of these 

 centres of eruption, however, those of Predazzo and Monzoni, are of 

 especial interest, from the numerous and interesting varieties of 

 igneous rocks which they poured forth. The name of '^ crater/' 

 which has been applied to some of the centres of eruption by Eicht- 

 hofen, is an unfortunate and misleading one, for nothing can be 

 more certain than that the different cones and craters have had their 

 original forms entirely destroyed by denudation, and that the remark- 

 able cup-shaped arrangement presented by the strata around each of 

 these points of volcanic action is due, as we shall hereafter see, to a 

 totally different cause from the explosive action that forms true 

 volcanic craters. 



The period of the formation of these several volcanic vents is that 

 of the Upper Trias. This was conclusively shown by Eichthofen, 

 whose well-known work on the district, published in 1858, was the 

 result of many years of patient study, and will hold its place (how- 



