THE GEOLOGICAL AGE OF CENTRAL AND WEST CORNWALL. 21 



This rarity of fossils is no doubt in part due to the rarity of 

 limestone rocks, but even where limestones do occur, as at the 

 Van, near St. Austell, in Grorran, in Grerrans Bay, in Betsy's 

 Cove near Porthalla, and at Newquay, very few fossils can be 

 found which are of much value to the Palseontological student.* 



On the other hand, the immense extent of the coast sections, 

 and the occurrence of a large number of inlets and creeks, affords 

 facilities for observations which are not available in many other 

 counties, and these facilities would be still more valuable were 

 it not for the greatly shattered state of the rocks on the coast, 

 and their very frequent displacement by landslips. f ' 



The Ladoch Beds. (Devonian ? Old Eed Sandstone ?) 



The most recent stratified rocks of central and west Cornwall, 

 — with the exception of the ancient stratified superficial deposits 

 of St. Agnes Beacon and elsewhere, — are remarkably well 

 developed in the parish of Ladock, — a few miles to the N.E. of 

 Truro, j These Ladock beds consist of a series of alternations of 

 dark-grey or bluish schistose strata, — at times almost like roofing 

 slate, — with others of a softer nature which are usually reddish 

 or yellowish ; together with a few beds of sandstone, occasionally 

 passing into a moderately coarse conglomerate, or a dark-blue 

 quartzite. These sandstones are very often soft and incoherent, 

 they consist almost entirely of angular^ grains of quartz, the 



* With regard to the rarity of limestones, I may mention that so far as I know, 

 not a single lime-kiln in the whole of the county is occupied in burning Cornish 

 limestone. ^• 



f It might have been expected that the deep excavations for mining purposes 

 would have afforded much valuable information of a stratigraphical nature. This, 

 however, is not the case to any great extent, — owing to the fact that the strata 

 are usually much disturbed and altered in the immediate neighbourhood of 

 mineral veins. 



X During the past five or six years, I have spent a good deal of time in exam- 

 ining the rocks between St. Austell and Truro, and some of the results of my 

 observations have from time to time been brought before the Eoyal Geological 

 Society of Cornwall, and also before the Geological Section of the British Associa- 

 tion. See "Preliminary Note on the Stratigraphy of West Cornwall," Trans, Boy. 

 Geol. Soc. Corn., X, 1, 1878; " On the Geological Structure of the Meneage 

 Peninsula," ibid 47, 1879 ; " On the Trelissick Elvan," ibid IX, 221, 1877 ; 

 " The Hensbarrow Granite District," Truro, Lake and Lake, 1877; and "On 

 the Geological Age of the Rocks of West Cornwall," Eejj. Brit. Assoc, p. 347, 

 Sheffield, 1879 ; " Eecent Analyses, &c." Journ. Boy. Inst. Corn, xxx, p. 408. 



§ Some of these sandstones have been recently described by Mr. J. A. Phillips. 

 See Quart. Jour. Geol, Soc, Feb. 1881, pp. 9, 10, 



