HOLMES] QUARRIES OF THE HIGHLAND 73 



employed in the tidew.iter region for stone iinplemeiits was not indig- 

 enous. It will now be desirable to study tlie origin and manufacture 

 of the exotic materials so extensively employed by tlie natives of tlie 

 lowland. 



The local materials wcie not of the best varieties, including little 

 else, as I have shown, than brittle (juartz and refractory quartzite. The 

 other materials sought in the highland at distant points are rhyolite, 

 jasper, argillite, and flint. All are found in limited quantity as pebbles 

 in the tidewater portions of the valleys in which they oc<'ur in place in 

 the highland, and the refuse left by arrow makers is found sparsely 

 scattered over the valleys. This refuse is closely analogous in its 

 forms with corresponding refuse resulting from the shaping of quartz 

 and quartzite pebbles. In some manner the natives of the lowland 

 acquired a knowledge of the location of the deposits of these mate- 

 rials in the highland, and (piarries were opened and worked and trans- 

 portation of the material, shaped or 2)artly wrought, became an 

 important industry. 



LOCATION AND PRODUCT 

 Khyolite Quawuks 



First in importance of the exotic materials used by the inhabitants of 

 the lowland is a variety of rather coarse-grain rock found in South 

 mountain, a high group of ridges extending from near the Potomac at 

 Harpers Ferry to the southern side of the Sus(iuehanna at Ilarrisburg, 

 Pennsylvania. It is an ancient eruptive rock of the acidic class, occur- 

 ring interbedded with other formations and outcropx)ing i7i narrow belts 

 parallel with the trend of the range. It is generally bluish gray in 

 color, though sometimes purplish, and is often banded and mottled by 

 what may be regarded as flow lines. Dark varieties closely resemble 

 slate, and the structure is often somewhat slaty, (ienerally it is 

 flecked with light-colored crystals of feldspar, by which character it is 

 easily recognized. Its fracture is often uncertain on account of a sha.ly 

 or laminated structure, but it is capable of being worked more readily 

 into large and long implements than any other of the several varieties 

 of rock found in the upper Potomac valley. 



The history of the discovery of this material may be of interest to 

 areheologists. On taking up the study of the tidewater region it was 

 observed that at least one-fourth of the implements collected were 

 made of a gray slaty stone. These objects were in the main knife-like 

 blades, projectile points, drills, etc, of usual types of form, though 

 occasional rudei' pieces and flakes were found. In a very few cases 

 larger masses of the rock were reported, one weighing several pounds 

 having been obtained from the banks of the Potomac opposite ilount 

 Vernon. It was of compact flakable stone, and although of turtleback 

 type had somewhat the appearance of a core or mass from which flakes 

 had been removed for shaping small implements. It may have been 



