THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 

 JULY 1843. 



I. Remarks on the Variegated Appearances of the New and 

 Old Red Sandstone Systems. By Captain James, Royal 

 Engineers, F.G.S., $c.* 



[Illustrated by Plate I.] 



TJTAVING in company with Sir Henry De la Beche and 

 •*•-*• Professor Phillips, examined a large tract of country 

 last year, including Herefordshire and Gloucestershire, where 

 both the Old and New Red Sandstone systems are so well 

 developed, I observed that that peculiarity in colour which 

 has obtained for the New Red Sandstone group the name of 

 Variegated or Poikilitic, was not due to any peculiarity of 

 colour in the nature of the sand or marl deposited, nor to 

 any peculiarity in the mode of deposition, but that it was due 

 simply and solely to a cause coming into action since the de- 

 position of the strata ; and in point of fact this variegated ap- 

 pearance is produced by causes which have discharged the 

 colour from groups of strata which were originally of a nearly 

 uniform tint. I shall proceed to illustrate this view of the 

 subject by sketches. 



At Garden Cliff, near Westbury-on- Severn, where a beau- 

 tiful section of the lower beds of the lias and the upper beds 

 of the New Red series presents itself, I observed that the pe- 

 culiar bluish-green colour (which at a distance gives the cliff' 

 the appearance of being composed of alternate strata of red 

 sandstone or marl, and strata of this colour) was not in reality 

 confined to the strata, but, on the contrary, that it extended 

 two or three inches on either side of the dividing planes of the 

 strata ; and again, that the same colour appeared at about the 



* Communicated by Sir Henry T. De la Beche, F.R.S., F.G.S., Con- 

 ductor of the Ordnance Geological Survey. 



Phil. Mag. S. 3. Vol. 23. No. 149. July 1843. B 



