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Oh Grooved and Striated Rocks in the Middle Region of Scot- 

 land. By Charles Maclaren, Esq., F.R.S.E., &c. (With 

 a Map.) Communicated by the Author.* 



Sir James Hall first called attention to the polished and 

 striated rocks in the valley of the Forth, in a remarkable paper, 

 read before this Society in 1812, and printed in the seventh 

 volume of our Transactions. He specifies four localities 

 where he observed them : At Torwood, about 4 miles north- 

 west from Falkirk ; at Corstorphine Hill ; at Fenton Tower, 

 in East Lothian ; and at Fass Castle, in Berwickshire. With 

 the striated rocks at these places he associated a peculiarity 

 of form, which is conspicuous in nearly all the low hills of 

 the same district, namely, that they present crags of bare 

 rock on their west, and deposits of soil on their east sides. 

 To this peculiarity he gave the descriptive name of " Crag- 

 and-Tail." The direction of the strise was nearly east and 

 west at Corstorphine Hill, WNW. and ESE. at Torwood, 

 Fenton Tower, and Fass Castle. He found examples of 

 crag-and-tail also in the west and south of Scotland, but 

 with different beai'ings. In the former, the crag faced the 

 east ; in the latter, it faced the north. After careful consi- 

 deration of the facts, aided by collateral lights derived from 

 other natural phenomena, he concluded that the strise and 

 grooves, and the smoothing of the surface, to which he gave 

 the name of dressing, must have been produced by fragments 

 of rock, gi'avel, and sand, driven over the land by a great 

 wave, or succession of waves, rushing from the Atlantic in 

 an east or south-east direction ; that one part of the wave 

 passed right across Scotland, grooving the rocks in its course, 

 laying bare the western fronts of the hills over which it 

 swept, and depositing tails of soil in the sheltered spaces be- 

 hind them ; that another portion of the wave was arrested 

 by the high mountains, and turned back, flowing ofi^' to the 



* Read before the Royal Society of Edinburgh on 2d April 1849. 

 VOL XLVII. NO. XCIH. — JULY 1849. L 



