242 HENRY S. WASHINGTON 



are Bucca' and Moderni.^ The former gives petrographical des- 

 criptions of the rocks collected by Moderni ; and the latter 

 describes the region from a geological point of view, giving a 

 quite detailed geological map on a scale of 1:100,000. Deecke 3 

 also touches upon the tuffs of the region in an article on the 

 tuffs of Campania. 



Topography. — The volcano of Rocca Monfina lies about 70 

 kilometers northwest of Naples, west of the main railroad line 

 from Naples to Rome. In the center is the trachy-andesitic 

 dome of Mte. Sta. Croce, 1005 meters above sea level, with the 

 smaller similar dome of Mte. Lattani (847 meters) adjoining it 

 to the northeast. These are steep well-wooded hills, made up 

 of solid masses of eruptive rock, with no tuffs nor signs of 

 separate lava flows. At the eastern foot of Mte. Sta. Croce is 

 the small town of Rocca Monfina, and extending around the two 

 domes, especially to the east and south, is the plain of the 

 same name. This plain (from 500 to 650 meters above sea level) 

 is bounded by the remains of a large crater ring, which is almost 

 circular in form and with a diameter of about 6 kilometers. 

 At the west and south the ridge, which is called Mte. Corti- 

 nelli, is quite high and sharp, reaching its maximum elevation 

 on the west at Mte. la Frascara (926 meters). Its inner slope 

 is very steep, while on the exterior it is very gentle, between 6° 

 and 10^. On the northeast and southeast the plain is bounded 

 by a series of hills which become less high as they are farther 

 from the center. This part of the crater ring has suffered 

 much from erosion, being furrowed by many deep radiating 

 ravines. 



In regard to the age of the volcano Moderni says that little 

 can be stated positively, except that at various places volcanic 

 material is seen resting on Mid-'^ ^.ocene beds. Deecke notes 

 the superposition of Rocca K^nhna tuffs on the gray Campanian 

 tuffs. It is probable that like the other volcanoes previously 



^BuccA, Boll. Com. Geol. Ital., 1886, 245. 

 ^Moderni, Boll. Com. Geol. Ital., 1887, 74. 

 3 Deecke, Neu. Jahrb. 1893, I, 62, 65. 



