340 Joseph Lucas — The Permian Beds. 



Limestone, but, even if they are, there is no reason why some limestone 

 pebbles should not have been transported into the basin, especially as 

 near the Swale nearly the whole of the Millstone-grit covering was 

 cut through before the deposition of the Permian beds. So far from 

 volcanoes occurring nearer than Scotland to this area, I think the 

 evidence seems rather to favour the idea of a continuous subsidence 

 having taken place here during the deposition of the Permian beds. 

 For the quicksands mentioned by Mr. Green, being excessively 

 current bedded, point to the close neighbourhood of land, inasmuch 

 as in an inland basin not subject to tides one would not expect 

 great irregularity in the bedding when the current had proceeded 

 some distance out. After the long interval between Leeds and 

 Crakehall, where there are no sediments except here and there about 

 five feet of flaggy and marly beds, the Marl Slate ^ of Durham comes 

 on. At East Thickley, where it is 30ft. thick, it contains " fish of 

 genera, which, from having all been found in Carboniferous strata, 

 probably lived near the shore." Now as on these quicksands, bare 

 Millstone-grit rocks from Leeds to Crakehall (presumably above 

 water when the quicksands and Marl Slate were deposited), and 

 Marl Slate of Durham there now lies a vast thickness of evenly thin 

 bedded limestones and marls, this fact seems to require SKe of 

 two things, either a continuous subsidence or a vast increase in the 

 supply of water to the basin, or both ; for up through the whole 

 series every part seems more like a shallow than a deep water de- 

 posit, and in the highest limestone itself, " some of the beds are 

 ripple marked, and Mr. King imagines that the absence of corals and 

 the character of the shells indicate shallow water." Li Scotland, 

 where volcanoes were active, we are clearly on the limits of the 

 basin, for in Dumfriesshire abundant reptilian footprints have been 

 found in sandstones. 



Thus it seems to me that if Carboniferous rocks formed part of 

 the coast land of the Permian Sea, there was an inexhaustible siipply 

 of all the materials which now form the Permian beds. The Car- 

 boniferous Limestone itself is sometimes Magnesian, as in the case 

 of the dun lime, and with regard to the peculiar bituminous smell 

 of the Magnesian Limestone when struck, I can only say that it is 

 far from being peculiar, and that Carboniferous Limestone very 

 often smells exactly the same. 



It seems also unlikely that active volcanoes existed nearer 

 to this area than where they have been proved in Scotland, 

 since the iron may have been supplied without volcanic springs, 

 direct from the Carboniferous formations, as well as from the older 

 granitic and other metamorphic rocks from which the Carboniferous 

 strata were themselves formed, and supplied with iron. 



The Purple Colour. 

 From Mr. Ward's paper, descriptive of the Plompton grits,^ it is 



' " The fish of the Marl Slate have generically strong affinities with those of Car- 

 boniferous age, some of which were undoubtedly truly marine, while others cer- 

 tainly penetrated shallow lagoons bordered by peaty flats." llamsay, Quart. Journ. 

 Geol. Soc, vol. xxvii., p. 248. '^ Quart. Journ. Geol. See, vol. xxv., p. 291. 



