466 THE CARBONIFEROUS ROCKS OF 



which forms the upper part of the Dairy and Kilbirnie Hills. At Wildshaw 

 near Douglas, however, it lies almost directly on the Old Red Sandstone. It 

 contains a large proportion of the marine fauna of the Carboniferous rocks of 

 Scotland. Near Campsie, Paisley, and Beith, it contains a bed with fresh- 

 water ostrocoda, and on the top of a thin coal below the lowest limestone 

 in the Beith and Dairy districts a band with Naiadites crassa. Above the 

 second limestone in the same localities and also at Kilwinning there is a 

 "fish-bed" in which volcanic debris mixed with the limestone is penetrated 

 by roots and rootlets of Stigmaria. Some of the beds of this series were at 

 one time very extensively worked for industrial purposes, but the workings 

 are now confined to a few opencast workings near Beith and some pits near 

 Lesmahagow. 



LOWER COALS AND IRONSTONE SERIES. 



This series occurs in a succession of strata between the Lower and Upper 

 Limestone series, and its economic bands of ironstone generally occupy the 

 lower part. The coals range from three or four workable seams at Dairy 

 and Kilbirnie to seven or eight at Dalquharran and Muirkirk where the 

 series attains its greatest importance. One of the seams near New 

 Cumnock was 40 feet thick, and the Johnstone coal is said to have been even 

 thicker. There are but few indications of marine conditions having obtained 

 during the deposition of the beds of this series, but many of freshwater 

 ones. Above one of the coal-seams near Giffen there is a thick band 

 crowded with Naiadites, and in the lower strata there are occasionally thin 

 layers containing some of the smaller species of Carbonicola. In the shales 

 associated with one of the ironstones huge spines of Gyracanthus are 

 sparingly got, also Rhizodus Hibberti, and sometimes reptilian remains. 



UPPER LIMESTONE SERIES. 



Like the Lower Limestones these strata attain their full development 

 near Dairy (the very thickest bed in the latter lies to the east of Beith), 

 but they are also well represented near Muirkirk and Barrhead. At the 

 last-named place one of the thicker beds has long been worked as a "cement- 

 stone." They, as a rule, contain more clay than the Lower Limestones, and 

 so have seldom been burned for lime, but some of them yield good hard 

 material tor roads. One of the lower beds, known as the "Index limestone" 

 is a "calm lime," that is, a limestone with almost no fossils large enough 

 to be visible to the naked eye, and breaking with a conchoidal fracture. 

 It has been largely used in iron-smelting, building, and agriculture. 

 Chert sometimes occurs in these beds as well as in the Lower Limestones. 

 Marine fossils are occasionally abundant in certain limestone bands 

 and in their under and overlying shales. Under the chief bed of 

 cement-stone at Dairy and at Thornliebank there is a hard shale with 

 Estheria and some crustacean remains, and the last of the trilobites occurs 

 in abundance at Bowertrapping. Corals are but feebly represented in this 

 series. Some thick and good white and grey sandstones occur in it. Nearly* 

 all the limestone beds rest, as in the Lower Limestones, with very little 

 intervening shale, on thin coal-seams with under clays. A few of these 

 coals swell out in places to a considerable thickness. I have come to the 

 conclusion that the Scottish Carboniferous limestones, as well as those in 

 the north of England, are sedimentary deposits, the finer limey material 

 of which they are largely composed having been brought by marine currents 

 from the sea-bed during shallow depressions of the areas over which they 

 extend. Plenty of evidence can be produced in favour of this view, but it is 

 too extensive a subject to be entered upon here. 



