ITALIAN PETROLOGICAL SKETCHES. 



THE VITERBO REGION. 



Bibliography. — The writings of the early Italian geologists, 

 such as Brocchi, Pareto, and Ponzi, are of such small petro- 

 logical value at the present time that nothing need be said of 

 them here. , , . - - 



The first to describe the region according to more modern 

 methods was vom Rath/ who devoted parts of two of his Italian 

 Fragments to its description. This is largely topographical, but 

 contains many petrographical details and some analyses, which 

 will be referred to later. Stoppani^ also, in 1873, gives a brief 

 account of the region. 



Through the kindness of Sig. Caposavi I was enabled to obtain 

 a copy of Dr. Barbieri's pamphlet, entitled / Viilca^ii Cimini e 

 Vnlsinii (Viterbo, 1877), which is out of print and very rare. It 

 proves to be a popular but graphic sketch of the geological his- 

 tory of this and the Bolsena regions. 3 



In 1880 A. Verri" published a somewhat extended descrip- 

 tion based on personal observations. Accompanying it is a 

 geological map, which is on a small scale, and a much idealized 

 section. His petrographical determinations are not based on 

 microscopical examination of thin sections, and hence leave 

 much to be desired. After the descriptions of the various rocks 

 and remarks on their distribution, he gives a sketch of the Ter- 

 tiary and post-Tertiary history of the volcano, as he deduces it 

 from his observations. 



'Vom Rath, Zeit. d. d. Gesell., XVIII, 577-585, 1866; XX, 294-307, 1868. 

 ^Corso di Geologia, Milan, 1873, III, 387. 



3 This is mentioned since the worlv is scarcely known, and the bibliography pub- 

 lished in the Boll. Com. GeoL Ital. for 1886 mentions it only by title. 

 ■^Verri, Atti Ace. dei Lincei., VIII, 3-34, 1880. 



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