854 



DR B. N. PEACH AND DR J. HORNE ON 



vii. Millstone Grit. 



Between the workable coal-seams of the Rowanburn group and the upper limestones 

 of the Marine Limestone series, as proved in the Rowanburnhead bore, there is a 

 succession of sandstones, shales, fireclays, and thin coal-seams, about one hundred and 

 eleven fathoms in thickness, which may represent, in part at least, the arenaceous group 

 (Millstone Grit) that intervenes between the Coal-measures above and the Marine 

 Limestone series below. Some of the bands of sandstone revealed in this bore are from 

 eighteen to thirty feet thick. During our recent examination of the district we had an 

 opportunity, through the courtesy of the manager, Mr Bowie, of studying the cores of 

 this bore, and paid special attention to these massive sandstones, some of which are 

 coarse, false-bedded, and pebbly. No plants have been collected from this horizon ; and 

 so far as this line of evidence is concerned, it is impossible to say where the boundary 

 should be drawn between the upper and lower divisions of the Carboniferous system. 



viii. Rowanbum Coal Group (Lower Coal-measures). 



This important group of strata contains the coal-seams which have so long been 

 wrought in the Canonbie district. The area uncovered by the stained red sandstones 

 of the Upper Coal-measures is about half a square mile. The strata are not exposed in 

 any stream section, and the information regarding the sequence of the beds and 

 geological structure of the field is based solely on mining plans. The following vertical 

 section supplied by Mr Bonar, present manager of the Canonbie Colliery, gives the 

 sequence of the coal-seams in descending order. 









Fm. 



Ft. 



Ins. 





Fms. 



Ft. 



Ins 



1. 



Upper coal . 









3 



4 



5. Three Feet coal 







3 



6 





Strata 





15 



4 



11 



Strata 



7 











2. 



Main coal 





1 











6. Five Feet coal 







5 









Strata 





12 



5 



-I 



Strata 



7 











3. 



Splint or Nine 



Feet coal 



1 



3 







7. Black top coal 







4 



9 





Strata 









4 







Strata 



4 











4. 



Coal (good) . 

 Strata 









1 



1 



Q 

 •J 



8 

 



8. Seven Feet coal (local name) 



1 











On referring to the geological sketch map of the district (Plate I.), it will be seen 

 that the coal-seams crop out to the west and north, being truncated on the south by a 

 powerful east and west fault that brings down the stained sandstones and shales of the 

 Upper Coal-measures. On their north-eastern side the strata are likewise bounded by 

 a fault which brings them in contact with the members of the Marine Limestone series. 

 The beds dip towards the east and south-east, and from the coal- workings it appears 

 that they curve up against the great bounding fault on the south side of the field at 

 Bowanburn (see Plate III. section 4). 



