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CHAPTER VIII. 



DEVONIAN AND OLD RED SANDSTONE ROCKS. 



IN 1836 Sedgwick and Murchison described the exist- 

 ence in Devonshire of a series of rocks bearing fossils 

 intermediate in character between those of the Upper 

 Silurian series and those of the Carboniferous Lime- 

 stone. This was done with the assistance of Mr. Lons- 

 dale in all the palseontological part of the question, in 

 which the argument chiefly lay. On these and certain 

 stratigraphical grounds, it was considered that they are 

 the equivalents of the Old Eed Sandstone of the centre 

 of England and of Scotland, and the name DEVONIAN 

 being applied to them, the terms Devonian and Old 

 Ked Sandstone are generally considered as equivalents 

 in point of geological time. 



According to the late Professor Jukes, the lowest 

 strata of the Barnstaple Bay district in North Devon 

 consist of red sandstones and conglomerates, similar to 

 those of part of the Old Red Sandstone of Ireland, and 

 not unlike that of the Mendip Hills. This, taken in 

 connection with the resemblance of the overlying strata 

 to the lower Carboniferous rocks of the south of Ireland, 

 led him to consider the chief part of the Devonian rocks 

 of Devonshire to be of Carboniferous age. To this con- 

 clusion he was led partly by palaeontological considera- 

 tions into which I cannot here enter. The opposite 



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