442 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 18, 



are difficult to make out. The plants reminded me of the flora at 

 Ardwick ; but better specimens are required than the flooded state 

 of the river allowed me to collect before thej can be identified with 

 those fossils. 



A little above the bleach-works bridge at Catrine is seen a bed of 

 red clays containing spheroidal bodies, having concentric laminae of 

 a greenish-blue colour, and containing a black speck in the centre. 

 For the whole distance between the old bridge and the bleach-works 

 bridge, the Coal-measures, especially the fire-clays, have a bright- 

 red appearance, and look as if they had been burnt. There appears 

 to be something like Stigmaria-rootlets in them, but not very di- 

 stinct. 



Beyond the red clays is a small bed of red gritstone, having fossils 

 bearing a resemblance to bifurcating stems, of about an inch in 

 diameter, on its surface. !N'ext comes a coarse-grained sandstone of 

 a purple colour, which is fractured by a fault running from north- 

 west to south-east, the extent of which cannot be seen. Proceeding 

 up the river, the strata soon again recover their original dip to the 

 west, and are seen in its bed up to Mmmo's Braes, where they dis- 

 appear and are covered up with soil. Opposite to the Burial- 

 ground at Sorn Castle a coarse-grained sandstone, of a red colour, 

 makes its appearance. It is of considerable thickness, and dips to 

 the west at an angle of 15°. It looks more like a Millstone -grit 

 than an Upper Coal sandstone, and contains white quartz-pebbles 

 of the size of a common bean. This rock reminded me much of a 

 pebbly bed of gritstone found in the upper part of the North 

 Staflbrdshire Coal-field, near Burslem. The strata, consisting of fine- 

 grained and laminated gritstones, continue past Sorn Suspension- 

 Bridge, where they dip to the west at an angle of 18°, to the Cleugh 

 Bridge. Coal-measures now and then make their appearance in 

 the bed of the river through Sorn up to the Coal -ford, near which 

 the strata appear much dislocated. Near this place a small seam 

 of coal, probably one of the upper beds of the Common series, had 

 been formerly wrought. 



It would be interesting to ascertain the exact position of this 

 seam with relation to the blackband-ironstone at Common worked 

 by the Portland Company ; for, if that could be done, all the Car- 

 boniferous strata from the Coal-ford at Sorn to the trap at Catrine- 

 Holm could be added to the Upper Coal-measures of Ayrshire, as 

 given by Mr. Ralph Moore in his valuable section. In a corre- 

 spondence which I have had with that gentleman, he states that the 

 seam of coal occupying the position of the Lanarkshire main coal 

 should be about 130 fathoms above the blackband-ironstone worked 

 by Mr. Lancaster, of the Portland Ironworks, at Common, near 

 Auchinleck ; and he places the Common blackband in the positions 

 of the slatyband-ironstone and the celebrated Boghead cannel-coal. 

 Mr. Lancaster, in a letter to me, states that he does not know much 

 about the Coal-ford seam ; but he thinks it has been worked for one 

 of the thin coals lying above the Common measures. This is very 

 likely to be the case, as the limestone-series of coals is seen on their 



