m 



TAB. CCCLXXXVIII. 



S I L E X quartzum. 



Strijied Flints. 



Div. 3. Amorphous. 



►Scotch Pebbles and Agates are most commonly known 

 in beautiful variety of concentric circles or laminae, and 

 have been in high estimation in jewellery, and still conti- 

 nue so. See tab. 160. Striped Flints are less known; al- 

 though not very uncommon, yet more rare than the 

 above, especially when the stripes are in circles, or con- 

 centric ; and they are only valuable for information, and 

 have in general less variety of colours and probably of 

 substance. 



The upper specimen is from King's Weston, near Bristol, 

 and consists of more or less condensed Flint ; the denser 

 parts are the darkest, and the lighter more or less porous, 

 and occasionally coloured of an ochraceous hue. The 

 present specimen is remarkable for having a hollow cen- 

 tre, and the circles being so extensive that when broken 

 externally it of course appears as if there were many cir- 

 cles and centres. Flints of this nature and of a larger 

 size are found at Woodford in Essex. 



The lower specimens are such as are found in the Gravel 

 near the Chalk Pits at Charlton, Plumsted, &c. These 

 are sometimes apparently parts of the larger sort, and are 

 more or less rounded by attrition, consequently showing 

 a later time than that of their formation for being depo- 

 sited in their present situation. 



The stripes in these instances seem to depend upon a 

 deposition of the parts while supported by Marie or 

 Clayey Rocks, and not upon laminae falling like strata t 

 one part imposed upon the other: — the lower pebbles 

 were thought to be of the latter construction. 



