™LMEs"''| QUARRY WORK AND MATERIAL. 9 



ways ou the other sides, as partially iudicated by the contours ou the 

 accompanying- map (plate i). The beds of chert, which are of upper 

 Subcarboniferous age, outcrop or approach the surface about the mar- 

 gins, forming in places a low, rounded scarp. The ancient implement- 

 makers began work at the more accessible i^oints along the margin and 

 gradually, no doubt, and by long continued operations carried their 

 trenches and pits far back into the surface of the terrace. 



THE MATERIAL QUARRIED. 



The chert worked by the ancient miners comprises numerous strata 

 of considerable aggregate thickness and doubtless of great horizontal 

 extent. Such exposures as occurred, or were made by my limited exca- 

 vations, were not suflBcient to give a good idea of the character of the 

 formation, but the fine blocks and masses thrown out and left by the 

 quarrymen indicate unusual massiveness and homogeneity. The frac- 

 ture is conchoidal to a high degree, although the surfaces are gTauular 

 rather than glossy, as in the flints. Flakes are removed with ease, and 

 the fracture carries remarkable distances. It is not unusual to find 

 flakes from six to ten inches in length, and they are often very attenu- 

 ated. They are highly resonant and jingle like bells beneath the feet. 

 Such portions of the chert beds as were uncovered by my workmen were 

 much flawed and fractured, but the solid portions seemed extremely 

 tough, refusing to break under the strokes of our light hammers. The 

 color, as seen in the quarried masses and refuse, is creamy white or 

 lig ht gray, with occasionally very delicate mottlings of pinkish, reddish, 

 aad yellowish grays. Freshly removed from the bed it seems to be 

 /jomewhat darker, resembling common varieties of horustone. It is 

 /not improbable that fires used in mining or from burning forests have 

 conspired to produce a chalky appearance in the surface fragments. 



EXTENT AND CHARACTER OF THE QUARRY WORK. 



In extent the work done in this locality does not compare with that 

 accomplished on Flint ridge in Ohio or in the novaculite quarries of 

 Arkansas, but was nevertheless quite extensive. The quarrying pre- 

 sents phenomena of unusual interest. 



There are three principal groups of the ancient excavations, as shown 

 on the map (plate i), the two clusters ou the western side being con- 

 nected by a narrow line of pits. The whole area covered by these dig- 

 gings does not exceed four or five acres. 



In the main the excavations took the form of roundish pits, but on 

 the margins trenches of a hundred feet or more in length were carried 

 along the ledges. Where the work was deep the refuse filled the pre- 

 ceding excavations and accumulated about the margins of the mines. 

 It is not ijrobable that many of the pits were more than ten or twelve 

 feet deep. At present the greatest depth is about five feet, and the 

 width of the roundish depressions rarely exceeds forty feet. In nearly 



