332 PROCEEDINGS OF THE GEOLOGICAL SOCIETT. [April 8, 



In the foregoing remarks I have assumed that the coal-fields of 

 Lancashire and Yorkshire were originally united right across the area 

 now occupied bj the Millstone-grit and Yoredale rocks of the 

 Pennine chain. That this was the case is abundantly proved by 

 the similarity (approximating to identity) of the strata of the Mill- 

 stone-grit series and lower Coal-measures on the opposite sides of 

 the chain. This resemblance, and the identity of special coal- 

 seams, has long since been pointed out by Professor Phillips, Mr. 

 E. W. Binney, and Mr. Warington Smyth*. 



System of North-iuest Faults. — Of later date, still, were those dis- 

 turbances which resulted in the production of faults and fractures 

 traversing the Lancashire coal-fields from IST.IS'.'W. to S.S.E., and 

 dislocating the strata to an extent amounting, in some cases, to more 

 than 1000 yards. 



Some of these fractures can be traced into Permian and Upper 

 Triassic strata — for example, the New Eed Marl of the Cheshire 

 plain. 



As these fractures are of more recent date than the Trias, we 

 must descend, in all probability, to the close of the Oolitic or 

 Jurassic period before we can arrive at the time of their produc- 

 tion ; for there seems to be no break in the sequence of the Tri- 

 assic and Jurassic formations after passing the Hue of discordance 

 which marks the boundaries of the Keuper and Bunter divisions of 

 the Trias. 



. We shall probably not err if we assign these fractures to disturb- 

 ances which occurred at the close of the Jurassic age, at the same 

 time admitting that they may have been modified at later times. 



To sum up — it seems probable, then, that the main lines of dis- 

 turbance may be assigned to three distinct periods : — 



1st and earliest (Pendle system), E.jST.E. direction, at the close 

 of the Carboniferous period. 



2nd, next (Pennine system), IS", and S. direction (nearly), at the 

 close of the Permian period. 



3rd and latest (lines of fracture), N.N.W. direction, at the close 

 of the Jurassic period. 



These may also be expressed by means of a triangle, the sides of 

 which are parallel to the direction of the forces (fig. 4). 



Foji 



Car^^H^ii^^ 



T Eig. 4. — Showing the relative ages and directions 

 ^ of the three 'principal systems of disturbance 

 after the Carboniferous Period. 



* Introductory Address delivered to the G-eological Section of the Britis 

 Association, Ifewcastle, 1863, pp. 10, 11 



