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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 26, 



March 26, 1851. 



John Kirkpatrick, Esq., and George Whitmore, Esq., were elected 

 Fellows. 



The following communications were read : — 

 1. On the Till of Caithness. By John Cleghorn, Esq. 

 [Communicated by Sir Charles Lyell, F.G.S.] 

 [Abstract^] 



The Till generally occupies the low districts of Caithness. At 

 Lybster, however, fourteen miles south of Wick, it reaches 212 feet 

 above the sea, with an unascertained depth below low-water mark. 

 In the harbour it has been bored twenty feet, and it is the anchorage 

 ground of the bay. The author finds that at Lybster and at Wick 

 the deposit is in a trough of rock, more than a mile broad and many 

 miles long, of the shape seen at a, b, c, in the annexed woodcut. At 

 Lybster the deposit is cut through by the Burn of Reisgill, which 

 empties itself into the harbour, and at Wick by the river of Wick ; 

 at both places the clay is found on each side of the watercourses, 

 rising in high banks, as shown at a, d, and e, c, in the accompanying 

 diagram. 



a d e c 



b 



From observations Mr. Cleghorn has had the opportunity of 

 making, he believes the Till to be laminated, as represented in the 

 accompanying section, and that the troughs at Lybster and Wick, 

 previously to the denuding action of the Burn and the River, were 

 filled up as represented in the figure. 



From the position of the Till in Caithness, its lamination, and 

 broken shells, from the occurrence of smoothed and scratched 

 boulders in the Till similar to such as are found in the watercourses 

 near Wick, and from the apparent elevation of the Caithness coast- 

 line, as proved by the occurrence of rocks perforated by lithodomous 

 molluscs at various elevations above the present level*, the author 



* This communication was accompanied by several slabs of micaceous limestone 

 covered by shallow pittings caused by marine molluscs (Patella) and weather- 

 worn in various degrees, which Mr. Cleghorn obtained at different heights above 

 the present sea-level. 



