578 



MR ROBERT KIDSTON ON 



Analysis of Table V. 



I have had little opportunity of examining the fossil plants from the Vobster Series, 

 where specimens are more difficult to procure than in any of the other divisions of the 

 Somerset Coal Field, with the exception of the Pennant Grit. 



Of the 8 species satisfactorily determined, 5 are found in the Upper Coal Measures, 

 of which 2 are characteristic of that horizon, 6 occur in the Middle Coal Measures, to 

 which 1 seems to be characteristic and 5 are got in the Lower Coal Measures, all of 

 which occur in the Middle Coal Measures. There is therefore a mixture of Upper and 

 Middle Coal Measure species in the Vobster Series, which shows they must be treated 

 as Transition Beds, and which cannot be referred to either typical Upper or Middle 

 Coal Measures. The Vobster Series are also therefore probably about the horizon of 

 the Lower Pennant Series of the South Wales Coal Field. 



The Pennant Rocks op Somerset. 



There still remains to be determined the relationship of the Pennant Pocks of the 

 Somerset Coal Field with the measures occurring in the South Wales Coal Field. 



The few fossils I have been able to identify from the Pennant Pocks represent so few 

 species that there is no palseontological evidence available for deciding this point. If, 

 however, we examine the fossil plants of the Upper Coal Measures which overlie the 

 Pennant, and compare them with those of the New Pock Series on which the Pennant 

 Pock rests, and which is clearly transitionary between the Upper and Middle Coal 

 Measures, the Pennant Rock of Somerset must obviously be either the basement beds of 

 the Upper Coal Measures or the upper portion of the Transition Series. Their position 

 would then, when compared with the rocks of the South Wales Coal Field, be between 

 the Upper and Lower Pennant Series of the South Wales Coal Field, or even perhaps 

 be of similar age to the Lower Pennant Series of that area, though, in the absence of any 

 definite palseontological evidence, one cannot positively determine their true position. 



The following table will show what I believe to be the relation of the Rocks of the 

 South Wales Coal Field to those of the Somerset Coal Field, and their position in the 

 general classification of the British Coal Measures. 



British Coal Measures. 



Somerset Coal Field. 



South Wales Coal Field. 



Upper Coal Measure* . 



( Radstock Series. 

 ( Farrington Series. 



Upper Pennant Series. 



Transition Series — between Upper 

 and Middle Coal Measures 



( 1 Pennant Rock. 

 | New Rock Series. 

 ( Vobster Series. 



Lower Pennant Series. 



Middle Coal Measures 



Absent. 



White Ash Series. 



Lower Coal Measures . 



Absent. 



Absent. 



