BY K. M. JOHNSTON, F.L.S. 



13 



The following summary may be of further interest in 

 showing the parallelism between the rocks of the two 

 districts : — 







Bore at 



Bore atHarefield f 





Mesozoic Rocks. 



Tarleton.* 









DEPTH. 



DEPTH. 



1. 



Upper coal measures, with 



Apparently 



About 270 feet. 





Thinnfeldia, etc. 



absent 







Carboniferous System. 







2 



Upper Marine beds, with 



Apparently 



32V feet. 





limestones containing 



absent 







Spirifera and Fenestella 







3. 



Lower coal measures, with 



Gangajuopteris, Schizoneicra, 



etc. 



Lower Marine beds 



About 200 feet 



98 feet. 



4 



IVO feet 



Apparently absent 





Devonian System. 



Apparently 

 absent 



Apparently absent 





Silurian System. 







5 



Upper Silurian slates, grits. 



Apparently 



40 feet where 





etc. 



absent 



depth of bore 

 reached. 



6 



Lower Silurian limestone. 



Pierced 36 feet 

 when drill 

 withdrawn 





* Mersey district. f Fingal district. 



It is probable that the lower coal measui-es of the Fingal 

 ■district are of limited extent, as the sections to the west and 

 north do not disclose their existence. To the east an. 

 important fault, throwing up the older rocks, cuts them off. 

 Jt would seem, therefore, that it is only possible for them to 

 show greater development in a southerly direction — that is, 

 towards the Fingal Tier, where the upper coal measures of 

 Mesozoic Age are again largely developed, abutting against 

 or underlying the greenstone rocks which characterise the 

 greater portion of the crest and upper levels of the tier. 



