NATURE, CHAEACTEE, AND ADAPTABILITY OF FLINT. 



20.3 



some West-Indian limestones the little Orbitoides and Nummulinae, and their 

 imbedding matrix, are silicified in varying degrees at different places*. 



However found, the nodules and bands of flint have yielded fit material for 

 human hands to fashion into sharp-edged tools and weapons, whether the blocks 

 were taken from the Chalk itself or other limestone, or from the rolled pebbles 

 and gravel strewed over countries where the Chalk has suffered degradation. 



The action of frost on a flint might result in the production of two or more 

 pieces, more or less triangular, with points and edges, and capable of being used 

 as rough cutting-instruments, or, being set with others like them side by side 

 along a stick, formed into a cutting-stick or armed club. 



Blows, also, and even pressure on a flint, if properly directed, produce angular 

 flakes, with sharp edges, owing to the mode of fracture that this mineral possesses, 

 somewhat after the manner of glass and resin, though it is less brittle than either. 



Given a solid block of flint, flakes may be struck off its sides f, and other flakes, 

 parallel to the first fractures, off the remaining surface, until the flint is reduced 

 to a small centre-piece bearing several narrow facets. Such a flaked piece is a 

 "core," from which one or more sets of flakes have been removed (A. Plate I.); 

 such a " core " or " nucleus " will be somewhat prismatic, and must be the result 

 of well-directed blows, striking off flakes or narrow laminae, having their axes in 

 one direction ; the blows, succeeding each other round the edge of the prism, 

 produce a succession of new narrow faces, bounded by parallel ridges or long 

 solid edges ; and these being carried away with the new set of flakes, each flake 

 will have one or two angles along its outside, or back, and a nearly even narrow 

 face Avithin (A. Plate II.). At the end of the flake where it was struck there will 

 be more or less of a convex swelling, called the "bulb of percussion," due to the 

 " conchoidal " style of fracture which the flint shows when smartly hit ; and the 

 further end of the flake will usually taper somewhat and have a curve, the hollow 

 of which fits against the " core." Obsidian J behaves in the same way under well- 

 directed blows or pressure, and, though more homogeneous, yields scarcely larger, 

 cleaner or neater flakes, razor-shaped and thin-edged, than flint will if carefully 

 selected and j udiciously handled. 



* Geological Magazine, vol. i. 1864, p. 102. 



t See Dr. Falconer's remarks on this subject in his paper on the Maccagnone Cave, Quart. Journ. Geol. 

 Soc., vol. xvi. p. 105. At the reading of this Memoir, June 22, 1859, Dr. Falconer fully illustrated the 

 process of " dislamination, as films, of the long angles of prismatic blocks of stone." The agate form of 

 chalcedony, also jasper, lydite, quartzite, and solid vein-quartz behave under blows and pressure similarly 

 to flint and its varieties above mentioned. 



t See Mr. E. B. Tylor's 'Anahuac,' 1861, pages 95-99 and 331. 



