XII. The Carboniferous Sediments around Strathaven

R. G. Carruthers
1915 Transactions of the Geological Society of Glasgow  
THE uplands of Lanarkshire are of abounding interest to the field geologist; they have long afforded material to both amateur and professional, so that certain parts may be regarded as classic ground. Of the less-known portions one of the most interesting is certainly the triangular area of Carboniferous rocks between Limekilnburn, Stonehouse, and Strathaven; nevertheless, apart from the Geological Survey maps and Ex planation (Sheet 23), no publications dealing with this ground seem to have
more » ... und seem to have appeared; the paper now presented is the result of revision work carried out for the Survey in the autumn of 1912. The strata in this region lie on the south-western fringe of the great Lanarkshire coalfield; they range from the base of the Coal Measures down to the Calciferous Sandstone Series, so that all the more important members of the Lower Carboniferous rocks are present, although one must confess that they are developed in an attenuated form. Broadly speaking, these strata are divided into four distinct areas 1 by a series of step faults, all with a downthrow to the north, and with a general direction east by south. It thus follows that the highest strata are let down in the most northerly of these fault blocks, namely, that in the Crookedstone district, between Limekilnburn and Darngaber Castle. Within the Crookedstone fault block the strata as a whole are inclined at a very gentle angle to the south-east. The lowest horizon may be taken as the band of limestone running through the hamlet of Limekilnburn; as this limestone has been extensively quarried in past times, the line of outcrop is easily 1 The chief interest attaches to the most southerly of these, and with that alone is the map accompanying this paper concerned. The existing Geological Survey 1-inch map (Sheet 23) gives an approximate idea of the other three areas. Library on June 14, 2015 at Carleton University http://trngl.lyellcollection.org/ Downloaded from 152 TRANSACTIONS-GEOLOGICAL SOCIETY OF GLASGOW. followed, but there is a corresponding difficulty in getting a view of the seam itself. The best exposure is on the south bank of the stream 700 yards due west of Quarter Road railway station; here the limestone is seen to be 4£ feet thick, with a ^-inch parting of blaes in the centre; it is a hard, pale grey stone, with porcellanous fracture and creamy weathering; fossilsare scarce, but a few small brachiopoda and crinoid ossicles canbe seen. Further down stream, immediately below the bridge at the keeper's cottage, a fault of 10 feet or so throws up the underlying strata, and at the top of the bank one can see that the limestone rests on blaes with brachiopods, &o., under which is an 8-inch bed of dark, slaty blaes lying on 4 inches of foul coal with fireclay below; at this point, in the dark slate above the coal, Mr. Tait has collected specimens of Edmondia punctatella, the characteristic index fossil of the Calmy or Gair Limestone position. This recognition of the Limekilnburn Limestone as the Calmy is confirmed by other evidence; a deep boring by the Shotts Iron Company on the north side of the stream 400 yards west of Browntod, started at the outcrop of the Limekilnburn Limestone, met the Orchard Limestone with its characteristic blaes at 18 fathoms, and passing through the Index Limestone (6 feet 8 inches thick) at 47 fathoms went on through the Coal and Ironstone group below, ending in the Lesmahagow Gas Coal position (Crutherlands Coals of East Kil bride) at 97 fathoms. In the stream passing under the main road south of Limekiln burn some 30 feet of blaes, with two thin bands of limestone, can be seen. These strata lie immediately above the Limekiln burn Limestone, and are of interest because they contain occasional crushed specimens of disiophyllid corals, fossils which are, as a general rule, exceedingly rare in the Upper Limestone group in Scotland. Higher strata ranging up to the Coal Measures are exposed further downstream east of Browntod; here there is a gently undulating sequence of sand stone, blaes, and fireclay. About 750 yards east of Browntod a thin band of parroty coal and blaes with Lingvla crosses the stream, and a few yards lower down there are excellent exposures of a hard, ochreous weathering, blue grey limestone containing a few small crinoid ossicles. Since the field evidence shows
doi:10.1144/transglas.15.2.151 fatcat:eh6skhevcjdcrmvwaoyuovkbne