DAVIDSON — SCOTTISH CAEBOXIFEROUS BEACHIOPODA. 



467 



rV. TheLoWEELlMESTONE-SERIES, 



about one Imndred fathoms 

 in thickness, consists of nine 

 or ten beds of Hmestone; coal- 

 seams of poor quality ac- 

 companj-ing, or rather lying 

 under, the last thi*ee ; yellow 

 and white sandstone, rather 

 sparingly developed ; vast 

 beds of shales becoming red 

 towards the base of the series ; 

 fire-clay, red in colour in the 

 lower beds ; numerous bands 

 of ironstone — resting on the 

 Old Red Sandstoxe. 



317 



337 

 338 



341 



343 



r Lingula-ironstone 

 Lingula-hmestone 

 1st Kingshaw lime- 

 stone 

 2nd Kingshaw lime- 

 stone. 

 I 1st. Calmy lime- 

 stone. 



Raes Gill ii^onstone 354 



Hosie's limestone 356 



2nd Calmy Hme- 371 

 stone 



Main limestone 



Shelly limestone 



Great Prodiidus 

 {cjiganteus) lime- 

 stone. 



Ironstone-bed, Pro- 

 ductus pundatus 



fathoms. 



375 

 391 



397 



400 



In all but the upper coal- series have Brachiopoda been found ; 

 they appear, however, more numerous in the second and fourth 

 divisions. 



No regular section or detailed account of the coal-formation to 

 the north of Glasgow appears to exist, yet it is e"S"ident from the 

 position of the strata, and the similarity of the fossils found in 

 the beds, that they also occupy the same stratigTaphical position, 

 as in the Carluke section, but with this important and notable 

 difference, namely, that the lower marine hmestones and shales con- 

 taining fossils in the parish of Carluke come very close iipon the Old 

 Ked sandstone, without any thickness of strata intervening; and 

 this seems also to be the case all along the south-western border of 

 the coal-field, while all along the north-western border the lower 

 marine limestone and shales are separated from the Old Red sand- 

 stone by an immense deposit made up of numerous alternations of 

 thin-bedded limestones and marly shales, with one or two beds of 

 red and grey micaceous sandstones, locally termed "Ballagan-" and 

 " Levenside-limestones," from the fine sections of strata exposed at 

 those places.* These beds had formerly been regarded by some 

 geologists as belonging to the uppennost member of the Old Red 

 sandstone, while others referred them to the Lower Carboniferous ; 

 and it was only recently, from Mr. Young having in three different 

 localities found fossils of a true carboniferous type, that these doubt- 

 ful beds, upwards of one thousand feet in thickness, could be referred 



* I am indebted to Mr, John Young for the iaformation I possess relative to 

 the strata to the north of Glasgow ; and to Messrs. Thomson and Armstrong for 

 that relative to Ayrshire and the neighbourhood of Glasgow. I attach much im- 

 portance to these districts on account of the great care with which the Brachio- 

 poda have been collected, and of which we will furnish complete lists hereafter. 



