54 /. W. Judd — On Volcanos. 



oft described examples of Yesuvius, Etna, the Auvergne, aud the 

 Eifel. 



Before we turn our attention to the evidences which are found of 

 the existence of volcanos in the same area during former geological 

 periods, it will be instructive to pause, in order to take a brief review 

 of the existing distribution of volcanic agencies in Europe. 



Excluding Iceland, there are in Europe five volcanos known to be 

 still active. One of these, Stromboli, is in a state of permanent 

 eruption, while the other four — Etna, Vesuvius, Yulcano, and 

 Santorin — may be the seat of a paroxysmal outburst at Sinj moment. 

 To these we ought perhaps to add the mud-volcanos of Sicily, Tran- 

 sylvania, and Wallachia. Some other volcanos, like the Solfatara of 

 Naples and the Biidos Hegy in Transylvania, still discharge con- 

 siderable quantities of heated gas and vapour, and are presumed 

 (though perhaps erroneously) to be approaching the stage of com- 

 plete extinction. Nor, in taking a survey of the volcanic phenomena 

 of Europe, ought we to omit to notice those innumerable sources of 

 hot water and gas, which perhaps collectively relieve the earth's 

 crust of more heat than escapes from it during all the outbursts of 

 volcanic violence, though in a manner so much less impressive. 

 These hot springs, rising probably in the lines of old volcanic 

 fissures, have determined the positions of the health-resorts which 

 are found in such abundance in certain parts of the Continent. 



But a large number of mountains and hills exist in Europe which, 

 although exhibiting few, if any, symptoms of igneous activity at 

 the present time, yet in their structure and materials present so many 

 points of analogy with the active volcanos which we have enume- 

 rated, that no one can for a moment hesitate in assigning to them a 

 similar mode of origin. Such are the innumerable extinct volcanos 

 in the districts of Southern and Central Italy, the Auvergne, the 

 Eifel, the G-recian Archipelago, the Island of Sardinia, and that lying 

 on both sides of the eastern end of the chain of the Pyrenees. 

 Besides these, several more isolated volcanic cones exist in Europe, 

 such as that of Orgiofhof in Moravia, and the well-known Kammer- 

 biihl and Eisenbiihl in Bohemia. Among these extinct volcanos 

 every possible gradation may be traced, from such as present the 

 most perfect and unweathered cones and craters, the complete extinc- 

 tion of some of which (as, for example, those of the Campi Phle- 

 grsei and Ischia) we are by no means assured of, to mere shapeless 

 heaps of volcanic materials. 



Besides the active and extinct volcanos, however, there are many 

 masses of rock in Europe which in character and composition betra}'' 

 unmistakable evidences of their igneous origin ; such are the so- 

 called '"traps" and many of the granitic rocks. Although the con- 

 nexion of these with volcanic, or indeed with any kind of igneous 

 action, was long strenuously denied, yet a more complete knowledge 

 of such rocks, and a juster conception of the trae nature of volcanic 

 action, has now removed all doubts upon the subject from the minds 

 of geologists,* who now recognize and reason upon the evidences of 

 volcanic activity in the earlier periods of the world's history with no 

 less certainty than concerning those of the present day. 



