238 Correspondence — Messrs. H. E. H. ^ Wm. PengeUy. 



TEEMINAL .CURVATUEE IN WEST SOMERSET. 



Sir, — The accompanying short extract from Sir H. de la Beche's 

 " Geological Observer," p. 23, 2nd edit. 1853. contains remarks so 

 apposite on this subject, that I trust Mr. Mackintosh will allow me 

 to call his attention to them, if he should happen not already to be 

 familiar with them. 



" The rain-waters not absorbed by the rocks, act mechanically on 

 the surface of the land, removing to lower levels such decomposed 

 portions of the rocks as their volume and velocity can transport. 

 The mixed effects of decomposition from atmospheric causes, and of 

 soaking of the surface on hill-sides, are often well shown in slate 

 countries, a certain depth beneath the soil exhibiting the turning 

 over of the edges of the slates towards the valleys ; — as it were the 

 tendency of the moistened matter of the surface to slide by its 

 gravity to the lower ground. 



"The accompanying figure" (showing highly inclined strata with 

 the upper portion beneath the soil bent over into a curvature ' against 

 their nap') "will illustrate this fact, one of much importance to the 

 observer, for without attention to it he might commit grave errors 

 as to the true dip of the strata, when only a slight depth of section 

 may be exposed on the hill-side. In the above figure the real dip 

 of beds is represented as the very reverse of that which might be 

 inferred from a hasty glance at the surface. Although it may be 

 supposed that the difference between this sliding down of the surface 

 towards the lower grounds and the true dip was always so apparent 

 as not to be mistaken, the depth to which this action has occasion- 

 ally extended is sufficient to justify great caution in many districts." 



It is to be remembered that ground that is now level may, at the 

 time when this curvature was produced, have been inclined towards 

 then-existing valleys. H. E. H. 



THE GORRAN BEDS AND BUDLEIGH SALTERTON PEBBLES. 



SiK, — I observe that in the discussion, on the 20th March, 1878, 

 on Mr. Ussher's paper on " The Chronological Value of the Triassic 

 Strata of the South-western Counties," as reported in the " Abstract 

 of the Proceedings of the Geological Society of London, No. 350," 

 "Mr. Etheridge said that he had been able to ascertain from 

 specimens in the Penzance Museum that the Budleigh Salterton 

 Pebbles came from Gorran [printed incorrectly Gowan] on the 

 southern coast of Cornwall," and that " Mr. Whitaker stated that 

 he had himself, on lithological grounds, suggested the Gorran 

 Haven region as a source for the Budleigh Salterton pebbles." 



These statements interest me a good deal, since they are con- 

 firmatory of those contained in the following quotation from a paper 

 which I had the pleasure of reading to the Plj^mouth Institution as 

 long ago as 30th March 1865 : — " Having learned that Mr. Peach 

 had lodged in the Penzance and Truro Museums such of the fossils 

 [from near Gorran] as he had collected, Mr. Vicary, Dr. Scott, and 

 I went into Cornwall early in July last (1864:), for the purpose of 

 examining them and the rocks in which they were found. The 



