160 Rev. A. Sedgwick and Mr. Murchison on Deposits in Scotland. 



The secondary rocks of Arran belong to the southern system ; and in the 

 coast section described in a former paper*, the several formations there ex- 

 hibited in one view are as follows : 



1st. Newer red sandstone and conglomerates. 



2nd. Coal-measures and mountain limestone. 



3rd. Older red sandstone and conglomerates. 



We believe that these older conglomerates are distinctly contemporaneous 

 with No. 10. of the northern series. The separation between the newer and 

 older conglomerates of Arran is clearly defined by the intervention of the coal- 

 measures and mountain limestone containing the characteristic fossils : and in 

 the northern extremity of Scotland^, the upper red sandstone is as distinctly 

 separated from the lower sandstone and conglomerate series,, by the interven- 

 tion of the ichthyolites and bituminous schist. In the absence of the charac- 

 teristic fossils and of the upper conglomerates^ we however consider the true 

 place of the upper sandstone of the Pentland Firth as in some degree am- 

 biguous. 



* See Plate III. and p. 24. 



