1862.] BECKLES REPTILIAN EOOTPRINTS. 443 



outcrop in the River Ayr above Glenlogan House. From the old 

 limestone quarry there to Sorn, the distance on the rise and dip of 

 the strata is 2040 yards, a space large enough for the outcrop of the 

 whole of the Common coals ; therefore, if we assume the Coal-ford 

 seam to be identical in position with the uppermost Ayrshire coal 

 in Mr. Moore's section, we have 12,940 feet as the distance between 

 the Sorn Coal-ford and the trap at Catrine-Holm, near where the 

 bed of limestone is found. This, on being divided by 4, assuming 

 the inclination to be one in four, which is about a fair average, 

 would give 3235 feet, or 539 fathoms, of strata. Probably the angle 

 of dip may, on the whole, scarcely average so much as one in four, 

 and faults may intervene so as to lessen the thickness ; but, making 

 ample allowance for these causes, there appears to be a thickness of 

 between 250 and 300 fathoms of Carboniferous strata in this 

 distance which has to be added to the top of Mr. Moore's section, — 

 a goodly addition of Coal-measures to the Scotch Coal-field, although 

 up to this time no seams of coal have been met with in it. 



7. On the Geological Stetjcttjee of the Southern Grampians. 

 By Professor James Nicol, P.E.S.E., F.G.S, 

 (Abstract.) 

 [The pubKcation of this Paper is deferred.] 

 The author stated that in 1844, and in subsequent years, he in- 

 dicated that the Siluiian strata of the South of Scotland are repre- 

 sented in the Worth by the metamorphosed or so-called primary 

 strata ; and he proceeded to point out that the object of the present 

 communication is to examine the relation which the three great 

 formations, Clay-slate, Mica-slate, and Gneiss, bear one to the other 

 as regular constituents of the crust of the earth, and especially in cer- 

 tain parts of the Scottish Highlands, as illustrated by sections observed 

 by himself. These he correlated with what is seen in other parts of 

 the Highlands. 



He also stated that, both in former papers and in his published 

 map, he has always regarded the gneiss of the west coast and certain 

 mica- or chlorite-slates of the interior as identical only so far as both 

 belong to the great series of metamorphic formations inferior to the 

 red sandstone and quartzite, but still as distinct formations with 

 pecuHar features, and, it may be, of widely different age. 



8. On some Natural Casts of Reptilian Footprints in the Wealden 

 Beds of the Isle of Wight and of Swanage. By S. H. Bece:les, 

 Esq., F.R.S., F.G.S. 



Since my last communication to the Society, in 1854, on the subject 

 of Wealden Footprints (Quart. Journ. Geol. Soc. vol. x. p. 456, &c.), 



