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THE CARBONIFEROUS ROCKS OF THE CLYDE 



DRAINAGE AREA. 



BY JOHN SMITH. 



THE Carboniferous strata of the Clyde drainage area, including the con- 

 temporaneous volcanic rocks and the later intrusive sills, reach a total 

 thickness of several thousand feet. Following the divisions adopted by the 

 officers of the Geological Survey the arrangement of the different series may 

 be given as follows : 



1. Upper Coal and Ironstone Series. 



a. Red Sandstone, etc. 



b. Coals, Ironstones, Fireclays, Shales, Oil-shales, White and Grey 



Sandstones. 



2. Millstone Grit Series. 



3. Upper Limestone Series. 



4. Lower Coal and Ironstone Series. 



5. Lower Limestone Series. 



6. Calciferous Sandstone Series. 



a. Cement Shales, and Grey Sandstones. 



b. Red or Grey Sandstones with Cornstones. 



Takino- these divisions in ascending order we have first the 



O O 



CALCIFEROUS SANDSTONE SERIES. 



The strata of this group rest either on Silurian rocks, as at Lady 

 Glen, Kilkerran, or on Old Red Sandstone, as near Sorn. The red or grey 

 sandstones of the division contain few fossils Lepidodendron, Calamites, 

 etc. and the Cornstone beds, once extensively worked near Galston, New 

 Cumnock, Kirkmichael, Dailly, Ayr, Arclrossan, etc., both in opencast 

 quarries and in mines, are now entirely abandoned. They are remarkable 

 deposits, sometimes with layers of chert, containing, amongst the limey 

 material, abundance of sand-grains, pebbles of agate, jasper, quartz, etc., but 

 they are entirely unfossiliferous. In the red sandstones near West Kilbride 

 occur footprints, probably reptilian, worm-trails, rain-prints, ripple-marks 

 and sun-cracks. The cement-shales in the upper part of the series occasion- 

 ally yield ostracods, fish-remains, and plants, as on the shore between the 

 mouth of the River Doon and the Heads of Ayr, and in the district between 

 Galston and Sorn thev contain thin lavers, some crowded with Spirorbis and 



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others with small bivalves. No truly marine remains have been found in 

 the Calciferous rocks of this area. 



LOWER LIMESTONE SERIES. 



This series may rest on the cement-beds, but where best developed in the 

 Beith and Dairy districts it rests on a great thickness of volcanic debris 



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