390 MR. TATE ON POLISHED AND SCRATCHED ROCKS, 
is very different from the rounding and smoothing of rocks, aris- 
ing from their attrition on each other by the driving action of 
tides and currents. I have carefully examined the condition of 
surfaces exposed to heavy seas, and of rocks which have, on the 
neighbouring coast, been rolled about, or driven onward by 
currents and the strongest tides ; but though these rocks, parti- 
cularly Limestones and Basalts, were smoothed and rounded, they 
never presented a bright and polished surface. 
Besides being polished, the Hawkhill Limestone was more or 
less scratched ; the scratches varying both in depth and in length, 
some being very fine strive, and a few being grooves + of an inch 
in depth. These grooves were parallel, one inch apart, and from 
6 to 12 inches long. Many of the scratches were 1-10th of an 
inch in breadth, and from 1 to 6 inches in length, having 
a general direction of from North to South, pretty nearly in 
the dip of the Quarry; but there were also other scratches, several 
being broad and deep, which were more or less oblique to the 
general direction ; those on the rounded corners of the higher 
parts of the surface, had a tolerably regular direction of from 
North West to South Hast. Notwithstanding, however, the 
exceptionable cases, the general direction of the scratches, when 
observed over the whole surface, could not be mistaken. 
The appearances described are undoubtedly connected with the 
boulder formation of the district ; for, in the bed of clay, above 
the polished limestone, there are polished blocks and fragments. 
A large block of limestone, measuring 3 feet long, by 2 feet broad 
and 2 feet thick, and embedded in the clay, three feet above the 
limestone bed, was scratched and polished on its under surface ; 
the scratches having a direction, as it lay, of from N.H. to 8.W. ; 
this block was not rounded like a water-worn stone. Smaller 
polished and scratched rocks are numerous in the clay, near to the 
limestone bed ; but the number of such polished fragments, pro- 
portionally diminish as we ascend higher in the clay deposit. 
On the opposite side of the valley of the Aln, the railway cutting 
through the clay, has exposed several blocks of limestone and 
basalt, similarly scratched and polished. In Scotland, in the Isle 
of Man, and other parts of England, and also in Scandinavia, the 
