BALDERSTON : THE SILURIAN ROCKS OF INGLETON. 1 35 



sea, and that the Upper Silurian conglomerate and tricleaved mud- 

 stones were first laid down in this area, which was often more 

 channelled and therefore deeper at the points where the softer and 

 more perishable Middle Llandeilo calcareous shales occurred. 

 Fossil, though somewhat indistinct, remains are to be found in the 

 mudstones and shales first laid down in such localities as the base of 

 the Upper Silurians. Existing sections through the coast-line or 

 across the estuaries and valleys of the period have in several cases 

 been described as "great faults," and the incorrect diagnosis has, 

 perhaps, been strengthened by some slight dislocation of the 

 formations in such localities, areas of greatest weakness and least 

 cohesion. It is easy to judge what geological conditions would 

 ensue on, what we may allow might be an uncommon example, the 

 submersion of something much less stupendous than the Sogne 

 Fjord of Norway. 



To me the evidence is unsurmountable that the Lower Silurians 

 run under the Upper division as moderately uniform and distinct folds, 

 almost vertical, but with a slight inclination to the S.W., never to the 

 N.E. ; to me these folds appear altogether independent of those of 

 the Upper series, which may be observed overlying the subjacent 

 beds almost horizontally as at Easegili and Pecca, or, elsewhere, 

 dipping at high angles to various parts of the compass in a manner 

 not observed in the rocks below, the successive folds of which 

 can be clearly identified, notwithstanding the few and distant 

 exposures before us. Who will be so bold as to allege any similar 

 uniformity in the upper series ? We advise those who are sceptical 

 on the subject to which we have drawn their attention, to once 

 more study the physical features of Wharf e, Helmsgill, Easegili, 

 Pecca, Crummach, Coombe, and Barkin Beck, Dowgill Bottom, etc., 

 from every standpoint and think out the problem for themselves. 



DETAILED ACCOUNT OF THE TRAP-DYKES. 



No. 1. — Iron-grey Dyke, (i) In the Twiss valley, less than 6 ft. 

 from the Tow Scar Fault, and there having a width of 24 ft. to 27 ft., 

 and a divergent branch 1 2 ft. wide, cutting through and dislocating 

 No. 2. (ii) By the Skirwith road, separated from the fault by about 

 75 ft. of dark, calcareous, cleaved slates, and here only 7 J ft. wide. 

 Externally much decomposed in the former position. Iron-grey to 

 black-green is the characteristic colour of the sound rock. The pale- 

 grey variety is more compact ; there are only two exposures. Its line 

 is evidently flexuous, a fact proved by its not appearing in the Doe or 

 intermediate positions, where it has, perhaps, been for some distance 

 faulted downwards. This dyke may be regarded as a mica-syenite, 



May 1889. 



