828 HENRY S. WASHINGTON 



The southern part of the region is included in the completed 

 Bracciano Sheet (Foglio 143, scale 1:100000) of the Geological 

 Map of Italy. 



Topograpliy . — The Viterbo region lies a few kilometers south- 

 east of Lake Bolsena, Viterbo being the chief town and best head- 

 quarters. It resembles in many respects the Bolsena region. 

 East of Viterbo and in the northern part of the region lies the 

 group of high hills known as the Monti Cimini, the early bul- 

 wark of the Etruscans against the Romans. The largest of 

 these is Monte Cimino, a curving ridge running north and south, 

 convex toward the east, its highest point 1053 meters above the 

 sea and about 800 above the plateau of Viterbo. Connected 

 with this and forming part of the same orographic mass are the 

 lower Monti di Vitorchiano, Soriano, and La Pallanzana. 



These, it may be said here, were formed by the older erup- 

 tions of the region. They are wholly built up of volcanic 

 materials — ^lava streams and beds of tuff and a tuff-like rock. 

 Stretching out around Monte Cimino to north, east, and west are 

 lava streams and beds of trachytic tuff. 



Immediately to the south of Monte Cimino, and southeast of 

 Viterbo, is the most striking feature of the region — the great 

 crater-ring of Monte Vico. This is almost circular in shape, its 

 symmetry being broken by the projection of Monte Fogliano in 

 the middle .of its western side. Its greatest diameter — from 

 north to south — is about five kilometers, and its widest part east 

 and west is nearly as great. 



The highest point of its rim is the summit of Monte Fogliano, 

 963 meters above sea level, the highest point on its northern 

 edge being 896 meters, on the east 696, and on the south 607. 

 It thus resembles the Bolsena, Latera, and other craters of Italy 

 in having its southern rim the lowest. The inner slope is quite 

 steep. Vom Rath estimates the average at 20°, which, judging 

 from my own observations, seems much too low. In places, as 

 on the east, and, according to vom Rath, on the south, it is 

 quite precipitous. When not hidden by forests of oak trees it is 

 seen that the walls are made up of beds of tuff with lava streams 



