ITALIAN PETROLOGICAL STUDIES. 



]V. THE ROCCA MONFINA REGION. 



The volcano of Rocca Monfina, was long celebrated as one 

 of the classical examples brought forward in favor of von Buch's 

 hypothesis of Craters of Elevation. Its historical interest is 

 equaled by its interest from a petrological point of view, since, 

 apart from the character of the rocks of which it is built up, 

 their order of succession forms an exception to that met with 

 elsewhere among the Italian volcanoes. My visit to the locality 

 was extremely brief and was confined to a trip from Teano on 

 the eastern border, past the central mass of Mte. Sta. Croce to 

 Conca, with one or two short excursions. I must therefore rely 

 for most of my knowledge of the volcano on the work of 

 others — a resource which in this case is somewhat meager. 



Rocca Monfina has been in fact one of the most neglected of 

 Italian volcanoes. The early works, chief among which are 

 those of Abich^ (who gives views and a map), Dauben}-^ and 

 Pilla 3 are devoted to an exposition of their views in favor of 

 von Buch's theory and the examination of the volcano from 

 this standpoint. They are therefore chiefl}' of historical value, 

 though Abich gives some descriptions of the rocks. Vom Rath'' 

 devotes a few pages of Part IV of his " Italian Fragments" to a 

 description and analyses of two of the rocks, which we shall 

 have occasion to notice later. A few others are briefly described 

 by J. Roth, 5 and Bucca's descriptions are quoted by Roienbusch. 

 The only modern writers who deal at all fully with the region 



'Abich, Vulk. Ersch. der Erde. Braunschweig, 1S41. 



^ Daubkny. Volcanoes, London, 1848. 174. 



3PILLA, cf. Neu. Jahrb. 1845, 843, and references in Moderni. 



•> Vom Rath, Zeit. d. d. geol. Ges. 243, 1873. 



? Roth, Geologic, IT, 245, 275, 354. 



241 



