Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/456

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Dr. Mac Culloch on the Geology of

the most musical, but we are not justified in changing them for so slight a convenience. The late introduction of a new chemical nomenclature, has possibly, in conjunction with other causes, excited a taste for neology, which it behoves us to restrain by every method in our power, and it is the duty of our Society to watch over and protect the science from those changes which will, if not restrained, shortly inundate us with as many names as we have writers.

The word killas, a vernacular and Cornish term, has been proposed as a substitute for graywacke. If killas were actually graywacke, we might have a fair plea for using the name given to it by a Cornish miner, in lieu of the corresponding one of a German miner. But this is not the fact, as those who are conversant with Cornish terms, well know that killas is applied to all the soil and fissile rocks occurring in Cornwall, whether clay slate, or graywacke slate; and that it is never used for either when they acquire the more compact and laminated form of roofing slate, a term as commonly applied to this variety in that county, as in other parts of England. The harder and more granular graywacke, is also called elvan, in common with trap, and other hard and dark blue stones.


It is well known that the ridge of which Ben Lomond forms a part, consists of micaceous schistus,[1] which terminates near Drymen in the highly elevated range of breccia that separates the primitive from the secondary country, and which may be traced from this

  1. In the Mineralogy of the Scottish isles, it is said that the summit of Ben Lomond consists of gneiss. It is necessary to correct this oversight, the whole of the mountain being formed of micaceous schistus, and no gneiss occurring in the neighbourhood.