Vol. 69.] SANDSTONE IN A BORING AT SOUTHALL. 81 



The presence of the Lower Greensand at Slough seems to indicate 

 that here we have a break, perhaps of the nature of a hay or other 

 inlet, into the Palseozoic land. . On the other hand, it may be that 

 the Palaeozoic mass, instead of continuing in an east-and-west 

 direction as generally assumed, may here swing round to the north 

 and join up with the Charnian axis. 



(2) The determination of the ' red rocks ' at Southall as un- 

 doubtedly of Old lied Sandstone age throws new light on similar 

 rocks recorded from other localities in the London district. In the 

 absence of fossils, all the evidence brought forward by Prof. Judd 

 for the post-Carboniferous age of the ' red rocks ' of the Richmond 

 boring would apply equally to the Southall rocks ; and this con- 

 clusion would have been strengthened by the discovery of dolomite 

 rhombs from the latter locality, an occurrence hitherto best known 

 from Keuper beds. As no fossils were found at Richmond, Cross- 

 ness, or Kentish Town, Prof. Judd was driven to make the utmost 

 of a careful lithological comparison with both Old Red and New 

 Red rocks, on the Continent as well as in this country. The 

 result of this comparison, confirmed by eminent foreign geologists, 

 was that there seemed to be a closer resemblance to post-Carbon- 

 iferous than to pre-Carboniferous rocks. Prestwich, however, 

 preferred to consider that the ' red rocks ' were of Devonian age, 

 and many later geologists have consistently spoken of them as Old 

 Red Sandstone, despite the difficulty created by the presence of 

 undoubtedly marine Devonian rocks in other borings under London. 

 Thus in the Royal Coal Commission's Report, already cited, these 

 rocks are referred to as ' Old Red Sandstone ? ' or ' [Old Red 

 Sandstone ?].' But such determinations always failed to com- 

 mand complete confidence, because of the want of palaeontological 

 evidence. Now that all doubt is removed in this one instance, it 

 may very well be considered that the rest of the ' red rocks ' are 

 also of Old Red Sandstone age. 



(3) The occurrence of particles of galena in both the Southall 

 and the Richmond rocks, together with the occurrence of dolomite 

 crystals in the former and sodium chloride in the latter, indicate 

 that the waters in which they were deposited were fairly con- 

 centrated. Again, the Southall rocks bear little resemblance to the 

 undoubted Devonian rocks from the Tottenham-Court Road and 

 Turnford borings, nor have they yielded any of the marine fossils 

 found at the other two localities. 



Appendix. — Note on the Fish-remains from the Upper Devonian. 



By Arthur Smith Woodward, LL.D., F.R.S., F.L.S., Sec.G.S. 



[Plate X.] 



The red sandy clay contains abundant fragments of the bony 

 dermal armour of fishes, but most of these are too small for 

 determination. When examined with an ordinary lens, a few 

 Q.J.G.8. No. 273. & 



