Mk. J. Betce on Coal Bearing Strata in the. Island of Bute. 49 



where a chemistry is at work which may only permit the metals to exist 

 in a pure, uncombined state. Pure metallic iron exists also in our trap 

 rocks. Dr. Thomas Anderson, at a late meeting of the Society, de- 

 scribed its occm-rence in the trap of Renfrewshire ; and Dr. Andrews of 

 Belfast finds it disseminated, in minute plates, in the traps of Antrim. 

 {Brit. Assoc. Report, 1852, Trans. Sec, p. 34.) Trap and other intru- 

 sive rocks are well known to be intimately related to the vast develop- 

 ment of gold in Australia, California, and the Ural. 



On Coal Bea/ring Strata in tlie Island of Bute. By James Betce, 

 M.A., F.G.S. 



Its a paper on the geology of Bute, which I had the honour of 

 submitting to the Society, on the 1st December, 1847, certain strata 

 on the shore at Ascog were referred with hesitation to the old red 

 series. They consisted of limestone and limestone breccia, sandstone, 

 shale, and coal, the whole capped by trap, and in some parts considerably 

 altered by overlying and intrusive beds of that rock. Very few fossils 

 had then been found in them ; none certainly of a character to determine 

 the age. Recently, however, fossils from the locality, which came into 

 my own hands and into those of my friend Mr. James P. Fraser, enabled 

 us about the same time, and independently of one another, to decide this 

 question, and without hesitation to refer the strata to the carboniferous 

 series. They seem to be upon the same horizon as the lower marine 

 beds of the Clyde basin, such, for example, as occur to the north-west 

 of Glasgow, and in the neighbourhood of Paisley. The strata hang on 

 to the flanks of the old red sandstone at Ascog, and are connected with 

 an isolated overlying mass of trap which appears on the shore, and 

 occupies the cliffs near Ascog mill. A portion of them are shown 

 in the annexed woodcut, taken from the paper already referred to. 

 The features are now shghtly altered by the action of the sea, which 

 is rapidly wearing some of the cliffs here. The section represents the 

 south side of the promontory, south of Ascog mill. 



On the north side of the promontory, several thin courses of nodular 

 limestone traverse beds of brown coloured crumbling shale, which is of 

 considerable thickness, and rises into banks west of the road. The 

 changes produced upon these strata by the proximity of the trap are 

 described in my former paper, and need not now be repeated. The 

 limestone shale and coal seams extend under high water mark ; and 

 when the tide is unusually low considerable pieces of coal are often 

 dug out from beneath the sand and mud covering the tideway. Work- 



VoL. IV.— No. 1. H 



