holmes] 



THE PINY BRANCH QUARRIES 



37 



sketched. The chaunel was about feet deep and 10 feet wide at this 

 point; the section across it, iucluding' both banks, is shown in figure 4. 

 The slopes of the terrace rise from the steep banks of this inner clian- 

 nel at an angle of from 20 to 25 degrees through a vertical distance of 

 60 feet, giving a distance (measured on the slope) to the summit ot 

 about 1(!0 feet on either side. This notch-like ravine is the result of a 

 long period of erosion, which possibly extends iar back into early 

 Cenozoic or even Mesozoic time. It had much its present outline, and 

 no doubt a greater part of its present depth, before man made his 

 appearance in the region. 



The area drained through this ravine is quite restricted, and, if 

 wholly wooded, the work of erosion would be extremely slow, the refuse 

 descending from the opposite sides so freely as to clog the channel, 

 save at the time of great freshets. The clearing of the fields at the 

 head of the basin has, in recent times, given some additional power to 

 the floods, and the channel is now not only quite clear, but bears evi- 



FiG. i — Section acrosa bed of rivulet at base of quarries. 



dence of considerable recent deepening. The gneisses are exposed on 

 the bottom and in the sides of the channel at the point crossed by our 

 section, save where covered by the half-compacted art-bearing talus. 

 The latter deposit is in places as much as S or 10 feet deep, and con- 

 tains innumerable relics from the great shops along the slopes above on 

 the right and left. An excellent illustration of the appearance of the 

 art-bearing debris, from a photograph taken at a point about 30 feet 

 below the initial i>oiut of the section, is given in plate iii. Partially 

 shaped implements and broken fragments project from the bank in 

 great numbers. The exposure here is 8 feet in depth, but the deposits 

 do not extend far into the bank, forming only a. veil over the irregular 

 surface of the gneiss. The latter is exposed beneath the left foot of 

 the standing figure and slopes back from the rivulet bed at a lower 

 angle than does the bank, as shown in the section, figure 4. 



A general view of the ravine looking up from tlie beginning of the 

 section is given in plate iv, and will serve to convey a clear impres.siou 



