- Div. 3. Amorphous.
Scotch Pebbles and Agates are most commonly known in beautiful variety of concentric circles or laminæ, and have been in high estimation in jewellery, and still continue so. See tab. 160. Striped Flints are less known; although not very uncommon, yet more rare than the above, especially when the stripes are in circles, or concentric; 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 centre, and the circles being so extensive that when broken externally it of course appears as if there were many circles 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 deposited 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 laminæ falling like strata, one part imposed upon the other;—the lower pebbles were thought to be of the latter construction.