48 STONE IMPLEMENTS [eth.axn.15 



the ]'otomac beds in ])l;u;e, ('ouiprisiiiff, first, about 3 feet of coarse 

 loose-bedderl sands of Auricd kinds, tlien alteruating layers of saud, 

 grave], and bowlders, ami at the base a (^nnpact layer of bowlders. 

 Tlie ancient workmen bad ])enetrated this latter bed at this jjoint only 

 to the depth of a foot or two. On the bottom and against the (piarry 

 face were a few chips and chii)i)ed bowlders, but the mass of material 

 filling up the ancient e.xcavation was barren of art and consisted of a 

 mixture of clay with sand and gravel, derived from the margins of the 

 ancient pit chiefly by sliding from the overhanging front wall. This 

 wall or (jnarry face as tmcovered by ns was only 12 or 1.'5 feet high, but 

 when the ancient miners deserted the spot it must have been very 

 much higher, probably 20 feet if the period was recent and perlia])s 

 more if the time was remote. As already stated, the configuration of 

 the slope showed that a slide had taken place, leaving a hollow Just 

 under the crest of the .slope and giving a rounded mass on the site of 

 the ancient digging. Eeneath the higliest part of this mass our trench 

 disclosed the deepest point reached by the aborigines. The filling up 

 by sliding en masse M'as thus shown by the surface configuration of the 

 site as well as by the character of the filling material. 



It appears that the bottom or floor of the ancient quarry was (juite 

 uneven, but its full conformation could not be made out from the dis- 

 closures of a trench 3 feet wide. In examining the sides of our trench 

 in the vicinity of the ancient quarry face I discovered that our left 

 wall had for several feet coincided here and there with the steep side 

 wall of the ancient excavation. 



The digging of this trench amply repaid the labcn- expended, as 

 answers were obtained to a number of the ([uestions presenting them- 

 selves. It was found, first, that the ancient quarrying was carried on 

 at a level only 2 or 3 feet above the present bed of the rivulet, and 

 second, that the trenches had been filled by sliding masses in such 

 manner as to produce inequalities of the surface not yet eftaced. In 

 addition, the conclusions reached by a study of the other trenches were 

 confirmed: 1, that there were well-defined quarries with quarry faces 

 of considerable vertical extent in the rotomac bowlder deposits; 2, 

 that little shaping was done in the deeper pits save that required in 

 testing the quality of the stone; 3, that the only work in the shops 

 about the excavations consisted in the roughing-out of leaf-shape 

 blades; 4, that the ancient diggings were extremely irregular, much 

 labor having been expended in exploitation and in reaching the heavier 

 deposits of workable bowlders; and, 5, that undermining was by no 

 means the exclusive method of reaching and securing the bowlders. 



Study of this trench afforded a remarkable instance of the confusion 

 possible in the association of works of art with gravel bluft's where 

 workable stone was sought. Had the cutting for a roadway or other 

 modern improvement been made along the side of this gorge the 

 exposures in the walls would have shown "implements"' embedded 



