6o 



HARDWICKE'S SCIENCE-GOSSIP. 



THE CARBONIFEROUS LIMESTONE OF 

 SCOTLAND. 



By Chas. Wardingley. 



THIS group of rocks has been variously termed 

 " Encrinital," " Productus " and "Mountain " 

 imestone, and in every case the synonyms have been 

 characteristically applied. The broader term " Car- 

 boniferous" is, however, to be preferred, as it will more 

 appropriately include all the varieties of limestone 

 tleposited between the close of the Old Red Sandstone 

 period and the commencement of the Permian. The 

 group is decidedly one of the most interesting of the 

 iossiliferous deposits of Scotland, and besides, affords 

 an excellent field of study to the practical geologist. 

 Outcrops occur in the large area extending from the 

 north-east of Fife to the south-west of Dumfries. In 

 these counties, and in Roxburgh, Haddington, 



desire to investigate the rocks for themselves, we 

 may divide the field occupied by the Carboniferous 

 Limestone into two sections, the Forth district, and 

 the Dumfriesshire district. The former affords the 

 greater number of accessible exposures, and besides 

 its geological features presents many other attractions 

 equally interesting to the tourist of scientific tastes 

 who desires to indulge in a variety of out-door 

 studies. 



The above rough sketch introduces us to the 

 limestone exposures adjacent to or within the Fortli 

 district, where the beds lie either immediately above 

 the Lower Coal Measures, or alternatively above the 

 Calciferous Sandstone Series. The total thickness of. 

 the beds does not exceed 90 feet, even including the 

 freshwater deposit familiarly known as the Burdie- 

 house Limestone. This is a great contrast to the- 

 enormous thickness of the limestone of Englandj, 



1 



1 



Q SCALE OF MILES 10 



TORPHICHIN Jt 



HILLS ^r^"^ 



$1^ oBATKGATE 



CILMERTON o 



OBURDIEHOUSE 



^DUNBAR 



OXHALLo If). 

 MAINS "XJCATS CRAGS 



Fig. 36. — Map showing Carboniferous Lirr.estone exposures in the Firth of Forth district. 



Edinburgh, and Linlithgow, it appears chiefly — as in 

 England, capping the various hills and ridges, having 

 to a considerable extent escaped by its hardness the 

 denuding and wasting influences which have worn 

 down the more friable sandstones. Compact and 

 durable, it has ofi'ered the sternest opposition to the 

 destructive powers of air, frost, and rain, with this 

 result, that while representatives of other formations 

 have been levelled to its base — the Carboniferous 

 Limestone still stands boldly and sharply out, its 

 peaks and ridges appearing to bid defiance to the 

 con<|uering power which has worked such havoc 

 among less resisting strata. 



To the student of geology the group is probably the 

 most unmistakable of the stratified rocks, and yielding 

 as it does a large variety of economic products, its 

 industrial importance can scarcely be over-rated. 

 For the convenience of tliose who may at any time 



where in several places, notably Ashbourne, in 

 Derbyshire, the total depth is over 1,500 feet. The 

 main mass of the Scotch limestone usually occurs in 

 thick beds, with but little shale [.between, and with 

 few exceptions is of the grey colour so familiar to 

 geologists who have worked the limestone deposits on 

 the south-western slopes of the Pennine range at 

 Chatburn, Clitheroe, and Whalley. Possibly the 

 best and most typical exposures will be found in Fife, 

 at Invertiel, i^ mile west of Kirkcaldy, and again at 

 Charleston, 5 miles west of the northern terminus of 

 the Forth bridge. At Invertiel it is seen lying upon 

 the Calciferous Sandstone, cropping out some 70 or 

 75 feet above the level of the sea, with the strike 

 running from N.W. to S.E. and with an E.N.E. dip 

 angle of 15°. The thickness of the exposed limestone 

 is about 30 feet, and for the greater part consists of 

 massive compact layers interspersed with thin seams 



