542 HENR V S. IV A SHING TO A 



are of little interest in the present connection. We may note, 

 however, that Pareto in 1844 pointed out three centers of activ- 

 ity, Latera, Torre Alfina and Montefiascone, around lake 

 Bolsena. 



Vom Rath' in 1868 gave a detailed description of the region. 

 His paper is largely topographical, with some descriptions of 

 the tuff and lava beds and a couple of analyses. He does not 

 consider the lake as the remains of one large crater, but thinks 

 that it is due to a sinking of the surface (^Ehiseiiktmg) , and that 

 the circle of hills was produced by eruptions at diiferent points 

 around this tract. 



Stoppani^ in 1873 gives a description of the volcano, in the 

 course of which he expresses his belief that the lake is in real- 

 ity the site of a vast crater, slightly enlarged by erosion ; at the 

 same time\ecognizing the existence of parasitic cones, of which 

 he gives Monte Rado near Bagnorea as an example. 



In 1888 Verri3 published a geological sketch of the region, 

 the rocks collected by him being handed over to Ricciardi for 

 chemical analysis and to Klein for petrographical description. 

 After a brief historical and topographical description he discusses 

 the order and epoch of the eruptions, and then describes in 

 detail the various eruptive centers around the lake. The origin 

 of this he holds to be that given by vom Rath. He considers 

 that the tuffs of the region were erupted in the condition of mud 

 — a conclusion, it may be added, which is strongly combated by 

 other Italian geologists. 



Klein's "^ article is composed of petrographical descriptions 

 of Verri's specimens, which include most of the prominent rocks 

 of the region. Though the descriptions are short and concise, 

 they give alVery good idea of the rocks ; and I am happy to say 

 that my own studies of specimens from the same localities sub- 

 stantiate Klein's descriptions in almost all points. The paper 



'Vom Rath, Zeit. d. d. geol. Gesell., XX, 265-294, 1868. 

 = Stoppani, Corso di Geologia, Milano, 1873, III> 37^, 386. 

 3 Verri, Boll. Soc. Geol. Ital., VII, 49-99, 1888. 

 4KLEiN,Neu. Jahrb., B. Bd., VI, 1-35, 1889. 



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