ITALY. LETTER XVII. 2$$ 



rife with the upper ends about twenty degrees 

 above the horizontal-line, dip with the under ends 

 in the mountain, and both ends entirely flat, not 

 convex or concave as the articulated Irifli bafaltes. 

 All along the roads about Bolzena many of thefe 

 prifms are raifed. The Ancients employed them 

 for grinding corn (Plin. lib. xxxvi. c. 18.) Kircher, 

 in Mufeo, mentions thefe Bolfena- bafaltes. Above 

 this ftratum of regular bafaltes, the mountain 

 confifts of the fame but undetermined lavaj 

 that is to fay, of a black compact lava, irregu- 

 larly cracked and broken - t though, in many places, 

 with fome tendency to a cryftalline form. The 

 white garnet-like fherls in the Bolzena-bafalt- 

 prifms are the fame as in the antique bafalt pe- 

 docchiofo, and other antique bafalts. 



This bafalt-hill is clofely fituated near the Ldgo 

 di Bolzena, and together with the other hills which 

 inclofe this lake ; but a remaining part of the old 

 volcano, which funk into the ground, and left 

 this water, fo as generally all fuch lakes in Italy ; 

 as Lago di Vico near Viterlo^ Lago di Bractiano, 

 di Nemis, and many more, are fuppofed to have 

 been produced. 



From Bolzena to slquapendente, are volcanic 

 ames and lavas, with white fherl-cryftallizations. 

 In the tufo-hills, near 6", Lorenzo die Grotte, I ob- 

 fervcd a great number of artificial caverns, being 



either 



