Fig. i 



Fig. 4. 



Fig. 5. 



Fig. i.— Specimen of slightly patinated flint scratched with a steel point. 



Notice the clusters of thin, minute plates of flint produced by the pressure of the moving point. 



Fig. 2.— Specimen of striated flint found upon the surface of the ground. 



veathering-out process has not in this case reached completion, and thin, minute plates of flint may b< 



seen at the sides of some of the striae. 



Fig. 3.— Specimen of striated flint found upon the surface of the ground. 



The weathering-out process has in this case reached completion. 



Fig. 4.— Specimen of flint with glazed surface scratched with a steel point. 



Notice the thin, minute plates of flint produced by the pressure of the moving point. 



Fig. 5.— Specimen of flint patinated white and scratched with a steel point. 



Notice how this comparatively soft surface has been cut into by the pressure of the moving point. 



598] 



