BALDERSTON : THE SILURIAN ROCKS OF INGLETON. 133 



due to the satisfactory identification of the succession and repetition 

 of these beds on each side of the centre of the fold, and the physical 

 features of the beds themselves. The thickness of the main 

 divisions so closely corresponds as to be sufficiently conclusive, 

 whilst that of the constituent and repeated beds of special character 

 is rather remarkable and not a very pleasant and satisfactory 

 argument for the support of the trap theory. Certain difficulties 

 necessarily present themselves to one working out these results, as 

 the galliards are not such a homogeneous series as may have been 

 supposed ; beds of green slate and felspathic ash are included, 

 galliard gradually passing into slate and ash, thus showing along the 

 outcrop of the same beds different stages of metamorphosis, whilst 

 in the centre group of purple, purple-black and iron-stained slates, 

 thin metalliferous veins, associated with chloritic vein-stuff, and all 

 the attendant features of thin extinction-dykes may be occasionally 

 observed as more characteristic of this group than of the Green 

 Slates and galliards. There, however, the most prominent object is 

 the large mass of Syenitic Gneiss, variously designated ' Basalt,' 

 'Conglomerate and Grits,' ' Quartz-Diorite,' etc., as the fancy of the 

 observer may have suggested, sufficient to stagger the field-geologist 

 at the very outset. Yet this rock was never ejected from a deep 

 centre, either as dyke or lava-flow, as is proved by the physical 

 condition and arrangement of its constituents. We observe bands 

 of slate running through it for a greater or less distance undisturbed, 

 thinner and more isolated bands similarly unchanged either in strike 

 or dip ; finally, thin slabs, pieces, particles, maintaining their original 

 relation to the green and other slates of the valley, and without 

 definite signs of fusion in what must have been a veritable sea of 

 molten matter, were the eruptive nature of the rock to be granted. 

 Neither can we detect on the margins of this mass a sufficiency 

 of evidence in the form of ramifications, extinction -dykes, meta- 

 morphosis of the adjacent slates, etc., to justify the conclusion that 

 it is igneous and not itself metamorphic. In the included slate 

 bands themselves, isolated and coarse-grained nuclei similar to the 

 surrounding rock may be obtained, and every stage and degree of 

 change are to be seen in various situations. 



In the face, then, of physical impossibilities and so much 

 evidence against an igneous origin, we are constrained to reject 

 this hypothesis, as well as the proposed alternative attributing a 

 conglomeratic origin to the rock, for either assumption leads to 

 absurdity, and the only decision left to us is, that the rock in question 

 was once part of the slate group, the oldest of the series and most 

 metamorphosed, without any very decided tendency to a schistose 



May 1889. 



