212 W. M. DAVIS — FAULT SCARF IN TIIK LEPINI MOUNTAINS 



just such a continuity of descent is beautifully developed at the base of 

 the Apennines where they descend to the Roman Campagna, as seen 

 northeastward from the train while climbing the Hank of the old Alban 

 volcanic group. 



The Piedmont Slope 



The Eocene strata recognized by Viola in the piedmont slope are for 

 the most part sheeted over by limestone waste, especially near the base 

 of the mountain front; but the general form of the slope is not express- 

 ive of well established grades. Although a great amount of limestone 

 waste must have been washed down across the piedmont slope, the expec- 

 tation suggested above of seeing there a forward extension of the grade 

 exhibited in the ravine floors and in the fans at the ravine mouths is 

 certainly disappointed. 



Drainage lines are continued forward from the mountain base, but 

 the interstream surface of the piedmont slope frequently has a jumbled 

 appearance, the adjacent parts not possessing that well organized rela- 

 tion to their drainage lines and to each other which always characterizes 

 an eroded surface that has been everywhere reduced to a graded form 

 under normal, undisturbed conditions. There is no well defined contin- 

 uation of the fan-like forms that are so well seen in the widened floors 

 of the rock-carved ravines. The irregularity in the distribution of lime- 

 stone gravel on the Eocene strata may be associated with the irregularity 

 of piedmont form. Instead of being an evenly spread sheet of waste 

 veneering the clays and forming laterally confluent fans — the forward 

 extension of the rock fans of the ravines — the gravels are present here 

 and absent there in rather arbitrary fashion. 



Near the spring known as Fontana Varico, just beneath the rock fan 

 of the third ravine north of Morolo, the upper part of the piedmont 

 slope is broken by a little scarp, partly of gravel. Farther forward, near 

 the lower border of the piedmont slope where it is about to descend be- 

 neath the alluvial plain of the Sacco, the irregularity of its surface takes 

 the form of uneven mounds. The floodplain, elsewhere perfectly level, 

 is here locally arched in the form of a flat dome 4 or 5 meters high 

 and from 70 to 100 meters in diameter. This interesting point may 

 be reached by a foot path across the fields, directly opposite Morolo 

 station, the most direct approach to the mountain front. The Sacco is 

 here crossed by a little foot bridge. All these local peculiarities of pied- 

 mont form suggest that some recent disturbance has replaced the orderly 

 piedmont slopes that should normally be associated with the carved 



