GEOLOGY OF BUTE. 333 



most zealous and successful. The Rev. Dr. Frazer, Paisley, 

 and Mr. Craig, Beith, have also done eminent service in the 

 same field. Mr. MacBride was the first to publish a division 

 of the beds, applicable to Bute, which has been since extended 

 by various researches, and the division may be considered to 

 hold true for all the beds in the west of Scotland. There 

 are local variations, but the division established by Mr. 

 MacBride represents the normal development of the series, 

 not only in Clydesdale, but generally over Scotland. The 

 Arran beds, we have seen, form one of the exceptions. The 

 series is shewn in its complete development at Kilchattau 

 Bay, close to the tile works. Mr. MacBride's order of suc- 

 cession (descending) is as follows : 



1. Vegetable soil. 



2. Sand and gravel, stratified and passing downwards into 

 a sandy clay, with gravel, 10 to 12 feet. 



3. Red clay, olive-green below, without stones or shells, 

 1 to 2 feet. 



4. Fine dark clay with arctic shells, 2 feet. 



5. Fine laminated clay, red or brown, without shells or 

 stones, 15 to 18 feet. 



6. Boulder clay, with striated stones; the upper surface 

 hummocky and irregular. 



Here bed No. 5 is the bed absent in Arran, but usually 

 present all over Clydesdale. It is a fine fissile clay, easily 

 opening into laminae like the leaves of a book, without 

 stones, and considered to be entirely unfossiliferous till the 

 recent discovery in it of foraminifera by Rev. H. "W. Cross- 

 key and Mr. D. Robertson; it is thus remarkably contrasted 

 with the boulder clay on which it rests. There are also here 

 indications of an upper shell bed. This section is contrasted 

 with those we have given in Arran (Art. 86), by the presence 

 of the laminated clay, always absent there, so that the bed 

 which is the main depository of the arctic shells rests directly 

 on the Till. Throughout Bute, on the opposite coast of Cowal 

 and Renfrew, and in most parts of Clydesdale, this laminated 



