16 



D. Mackintosh — Age of Floating Ice. 



neath wliicli the yellowish brown clay, underlain by the blue, rises up 

 from under the sea. At one point there is a very curious dove- 

 tailing of the blue into the brown clay. Some distance seaward 

 from Khos village, the blue clay mates its appearance at low water. 

 Beyond Khos village, the yellowish brown clay becomes very con- 

 spicuous, and resembles a local subdivision of the Lower Boulder- 

 clay which may be traced along the sea-coast of Cumberland, 

 Lancashire, and Cheshire. It is lost under sand, again shows its 

 face, and further on, beyond Ehos Point, overlies undulating bosses 

 of the blue clay, which there appears in full force. 



New 

 Hotel. 



Fig. 1.— Coast-section of a Part of New Colwyn Bay. 



Khos. 



Rhos Pt. 



Blue Clay. 



2. Lower brown clay. 



3. Sand and gravel. 



Blue Clay. 

 4. Upper red or brick clay. 



Peculiarities of the Blue and BricTc Clays. — The dark blue, bluish- 

 grey, or sometimes bluish-green clay, is pack-full of small stones, 

 and, in its lower part, larger stones mixed with enormous boulders. 

 It may have been principally derived from the grinding down of the 

 dark Silurian shale or slate which may be found in the neighbour- 

 hood. The smaller stones are generally flat oblong fragments of 

 dark shale or slate. Their form must have interfered with their 

 becoming rounded by rolling, but where stones of a different nature 

 are found in the same clay they are often well rounded. They are 

 generally scratched on both sides in nearly every direction, but 



Fig. 2. — Both sides of a striated stone from tlie Colwj^n Blue Clay. 



seldom distinctly grooved. They look as if they had been ''bandied 

 about " while entangled in coast-ice, which finally left them imbedded 

 in the clay. The large boulders^ reach an average diameter of seven 

 or eight feet near Ehos Point, and consist chiefly of limestone, a 

 gritty rock with veins of calcareous spar, a greenish rock graduating 

 into porphyry greenstone apparently of the Welsh type, Silurian 

 hard shale or slate, volcanic breccia, etc. They may nearly all have 

 come from the neighbourhood ; but as I dug out of the blue clay 

 two pebbles of Eskdale granite, and found one of Criffeli granite on 



1 They seldom exhibit marks of much flattening through grinding, though some of 

 those which consist of limestone are so irregularly scratched all round, that a gentle- 

 man from Chester, who disbelieved in a Glacial period, contended that a party of boys 

 had been disfiguring the boulders in play. 



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