208 W. M. DAVIS — FAULT SCARP IN THE LEPINI MOUNTAINS 



by the laborious peasants of the neighboring villages. Whole families 

 may be seen working together, from grandparents to grandchildren — 

 lathers and mothers, sons and daughters. The railway follows the eastern 

 border of the plain. On looking westward to the mountain base, a dis- 

 tance of about 3 kilometers, one may see a bare rock} 7 scarp, with a height 

 of 30 meters or more, following along the base of the steeper mountain 

 front, above a gentler piedmont slope that descends to the alluvial plain. 

 When this scarp was first seen, on my way to Naples, it recalled very 

 distinctly the little cliffs produced by faulting in the western base of the 

 Wahsatch range south of Salt Lake City, as exhibited to the excursion- 

 ists of the International Geological Congress of 1891, while under the 

 guidance of Mr Gilbert; so I resolved to have a closer look at the base 

 of the Lepini mountains after returning to Rome. 



The villages of Scurgola and Morolo lay close to the line of the scarp 

 near its northern and southern ends, as well as could be seen from the 

 train, with a distance of about 8 kilometers between them. Local rail- 

 way stations of the same names served as the beginning and end of two 

 excursions on foot a fortnight after my first sight of the place. 



Local Geology 



Betw r een two visits to the Lepini fault scarp 1 had opportunity at the 

 office of the Geological Survey in Rome of looking over what has been 

 published concerning the geology of the region in question. The most 

 important articles are by C. Viola,* from whose reports and from the 

 geological map of the district it appears that the Lepini mountains con- 

 sist of a great mass of Cretaceous limestones, here and there capped with 

 Eocene beds, all uplifted and moderately deformed and separated from 

 the Eocene of the Sacco valley on the northeast by a strong fault trend- 

 ing northwest and southeast, with a dislocation of 1,200 meters or more. 

 Several small Quaternary volcanoes, now extinct, are described on the 

 more southern part of the fault line. 



The Mountain Front 



A view of the mountain front, as seen from Morolo station, shows 

 the fault scarp along the mountain base very clearly. No account of 

 the scarp will be given in the present section of this article, which deals 

 only with the slope above the scarp. 



* Osservazioni fatti sui monti Lepini. Boll. R. Comm. Geol. cT Italia, xxv, is<j4, 152-159. 



Le ViilU' del Sacco, etc. [bid., xxvi, 1895, 136-143. 



Cenne delle osservazioni fatti sui monti Lepini nel lsi»4. [bid., xxvi, 1895, 322-325. 



