HOLMES] THE PINY BRANCH QUARRIES 43 



Tlie quarry face (plate xiii) was eiicouutered at about the eiglitieth 

 foot, but sloped back iu steps to the ninetieth foot and beyond. It 

 showed a stratum, 10 feet or more in thickness, consisting hirgclj' of 

 medium size quartzite bowlders embedded iu a matrix of nearly pure 

 sand, so indurated that the bowlders were extremely dififlcult to remove, 

 and considerable masses of the conglomerate could be knocked down 

 and removed without breaking up. The face was extremely irregular, 

 indicating that when deserted the ancient quarrymen had penetrated 

 to greatly varying depths; they had descended to the gneiss surface 

 in excavations from 10 to 12 feet deep, had removed the bowlders by 

 direct attack from above, from the front, and by undermining, and had 

 selected and thrown out those best suited to the purpose of the tlaker. 

 Few of those left in the pits and dump had been more than tested by 

 the removal of a flake or two. The work of shaping was iu the main 

 carried on about the margins of the pits out of the way of the quarry- 

 man. The earth, gravel, and undesirable bowlders were thrown back 

 against the lower side of the pits, lodging in irregular beds sloping 

 into the pits, as shown in the section. 



Between the seveutythird foot and the seventyeighth our trench 

 passed through large pockets or masses of shop refuse. The largest 

 body, consisting of tons of chips, failures, and bi-oken bowlders, was 

 contiued to a space extending from 3 to 7 feet from the surface: smaller 

 pockets of the same character were found as deep as 9 feet. The 

 exposure in the sides and front of our trench showed these deposits 

 clearly, and illustrations are selected from the fine series of photo- 

 graphs taken. Plate ix represents nearly the full height of the front 

 of our trench at the seventyseventh foot, and plates x and xi illustrate 

 the composition of the refuse in detail, showing a preponderance of 

 rather large bowlders, most of which have been partially worked or 

 broken to test the material. The portion shown in i)late xi belongs 

 lower in the section, extending down from the seventh nearly to the 

 ninth foot in depth. Several shaped pieces are in sight. In i)late xii 

 we have a fine illustration of the clusters of shop refuse at about the 

 eightieth foot. The clinging wet earth obscures many of the fine Hakes, 

 but enough is seen to indicate the very great amount of work done on 

 this spot. The mass was made up of unshaped refuse and of shaped 

 specimens, illustrating the whole range of cpiarry-shop work from the 

 first flake to the rude thin blade; the latter, it was gradually learned, 

 being the almost exclusive pi'oduct of the flaking operations. A sec- 

 tion showing the quarry pit and the face of Potomac bowlders is pre- 

 sented in plate xiii. This terraced face, receding in irregular steps, 

 appears to have undergone little change since it was deserted by the 

 prehistoric quarrymen. The bowlders are compactly bedded and retain 

 their places with great tenacity. 



The deepest work of which evidence was discovered was about 11 

 feet beneath the present surface. It is probable that when deserted 

 the pit at the quarry face was much deeper, as considerable degra- 



