PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 24, 



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Ardrossan. 

 Fault. 



Quarry. 



Fault. 



Ardneil, 



Portencross. 



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Goldenberrv 

 Hill, 



been forced 



proof by superposition is wanting : 

 no fossils, I believe, have been found 

 in the red sandstones ; and the coast 

 of Arran opposite gives an example 

 of sandstones and conglomerates 

 indistinguishable in mineral type, 

 some superior to, and others under- 

 lying the coal-measures. Having 

 lately discovered a patch of Silurian 

 rock in this district, which appears 

 to me conclusive of the age of the 

 sandstone series, it may be worth 

 while to give details of the section. 

 From Saltcoats to Ardrossan (see 

 fig.) the coal-measures are seen on 

 the shore, dipping S.E., and con- 

 sisting of the usual alternations of 

 sandstones and shales with imbedded 

 plants, beds of coal, and limestone. 

 Approaching the harbour of Ardros- 

 san, these beds dip S.E. at an angle 

 of 45°, when a mass of trap sets in, 

 which, running out to sea, forms a 

 natural breakwater. To the north 

 of the trap begin the red sand- 

 stones, also dipping S.E., but at a 

 lower angle. They are well ex- 

 hibited in a quarry immediately 

 north of the town. The top beds 

 are of a marly nature ; and it is 

 only near the bottom of the section 

 ■^ 1 ^ that the strata contain a few pebbles 

 of white quartz. Por four miles the 

 shore is composed of the same forma- 

 tion, still dipping S.E. until we 

 reach a point where the beds for 

 a short distance dip N.W., at a low 

 angle ; a little further to the N., 

 near the House of Ardneil, the sand- 

 stones are vertical for several yards, 

 after which we arrive at a spot where 

 a sudden change in the rock, attended 

 with the greatest disturbance, is 

 exhibited. A mass of light- and 

 dark-green, claret- coloured, and 

 black shales and arenaceous schists, 

 veined with calc-^spar, and contorted 

 in every conceivable way, has here 

 up through the sandstones and conglomerates, which, 



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