Correspondence — 3[r. John Smith. 191 



clay " — exported to France. About the middle of the dock works 

 this so-called "china clay" was yellowish at the top part, whitish in 

 the middle, and bluish at the bottom. It is exceedingly fine- 

 grained, cm be scratched with the nail, and falls to powder readily 

 on exposure to the weather ; but when put into an open fire and 

 raised to a good red heat it will scratch glass. 



D. This bed is perhaps just an extra-dark band of C. 



E. Transition bed from D to F. 



F. This bed does not differ from the real Water of Ayr Hone or 

 Whetstone, and has already gained a reputation as a whetstone and 

 polisher. It is of various shades of coloqr from light grey to dark 

 grey — the lighter the colour the softer the material — but they all 

 show the peculiar " mirl " of the Water of Ayr stone. Bed E has 

 also this " mirl," showing that it is a transition stage between the 

 " china clay " and the " Hone " bed. 



All the beds below the trap exposed in the dock works are perhaps 

 just fine volcanic dust deposited in water, and some of them are more 

 or less stratified, although the stratification is often very faint. 



The Hone bed contains nodules of a greenish material with a little 

 pyrites and mica (white), some of the nodules showing concentric 

 rings towards the outside; and the bedding planes of E have a slight 

 sprinkling of mica. 



The trap B is probably an intrusive bed — Whin Sill — and has 

 hardened the "china clay" at its junction with that material. This 

 hardening is well seen towards the north end of the dock, where 

 the clay has been somewhat mixed up with the trap. On the 

 west shore of Troon Point, trap, very coarse in appearance 

 from weathering, is also seen at one or two points to have clay 

 inclusions, the clay in both the above cases being converted into 

 hornstone or porcellanite, and this substance, like the heated clay, also 

 scratches glass. 



The position of the beds is somewhere in the Upper Coal-measures 

 (of Scotland). 



The Water of Ayr Hone-bed crops out near Carreath, three miles 

 east from the dock section, and is at present worked in two places, 

 on the Ayr Water to the south of Torbolton, as a polisher and 

 whetstone, ten miles south-east from the dock section. This seems 

 to point to a powerful Carboniferous volcano having existed in the 

 neighbourhood, the fine dust from which appears to have been 

 deposited in pretty still water (probably fresh). Ferns (which 

 I have seen) have been found embedded in the Hone-stone at the 

 Water of Ayr Works. 



In the dock section I observed no organic remains, but some 

 parts of the " china clay " bed have faint light-coloured markings, 

 suggestive of worm-tracks. John Smith. 



P.S. — On Saturday last a number of the members of the Geological 

 Society of Glasgow, at my invitation, visited the Troon section and 

 were much pleased with what they saw, the Hone or Whetstone 

 bed being an entirely new deposit to all of them. — J. S. 



MONKREDDING, KiLWINNING. 



nth March, 1898. ' 



