﻿452 Horace B. Woodward — Notes on the Devonian Rocks. 



"While I would not for a moment suggest that an accurate parallel 

 of the strata could be made on lithological any more than on palaeon- 

 tological grounds alone, yet we cannot overlook the resemblances. 



It cannot be doubted, however, that we must be guided by the 

 stratigraphical facts, and most important is the relation that the 

 Devonian Limestone bears to the Culm-Measures above. 



While I have indicated the facts of the succession in the strata 

 near Newton Abbot and Torquay, there are many places where the 

 relations of slates and limestones are not clear. 



The mass of limestone that extends from Lyndridge to near 

 Kingsteignton dips to the south-east at angles of from 20° to 30°. 

 The boundary-line with the Culm-measures to the north runs along 

 the bottom of the valley, and no junction sections are to be seen. 

 The same is the case south of Ideford, where, instead of there being- 

 three small masses of limestone in the midst of the Culm-measures, 

 there is but one mass, abruptly adjoining these newer strata. The 

 Culm-measures at Combe, Heston, and Whiteway Farms dip to the 

 south-east as if they would pass under the Devonian Limestone. 

 Hence, if the beds be not actually inverted, there must be a con- 

 siderable fault running along the valley between Lyndridge Hill and 

 Ideford. An inversion might help us to account for the mass of 

 limestone stretching from Oldchard Well to Ugbrooke House. Its 

 relations with the Culm-measures are nowhere exhibited, but these 

 beds are seen to be violently disturbed by the high-road west of 

 Bellamarsh Wood ; here, however, the great fault that cuts off the 

 Chudleigh Limestone may pass. Again the Devonian slates that 

 extend from Bishopsteignton to Kingsteignton, and which near Wear 

 Cross would seem to overlie the limestone, are nowhere clearly 

 shown in I'elation to it, and are highly disturbed in places by the 

 great intruded mass of igneous rock. There is clear evidence 

 in the cliffs north of Teignmouth of a fault which runs through 

 Bishopsteignton. 



Nowhere have we any positive evidence of a mass of Devonian 

 slates overlying the limestone. In some places, near Oldchard W^ell 

 and Abbots Kerswell, I have seen traces a foot or two in thickness 

 of blue and purple shales resting upon the limestone, and this would 

 accord with the facts obtained by my colleague Mr. Eeid at Chud- 

 leigh, where the Devonian Limestone is only separated from the 

 Culm -measures by a thin bed of shales. 



This question of the relations of Devonian rocks and Culm- 

 measures is full of interest, and full of puzzles. Authorities agree 

 that the Culm-measures represent a part of the true Coal-measures, 

 and probably include the whole of the Millstone-grit. Both Mr. 

 Godwin- Austen and Dr. Holl have maintained that in South Devon 

 the Culm-measures rest unconformably upon the Devonian rocks. 

 Some of the evidence relied upon by the former, and quoted by the 

 latter, has been shown by Mr. Eeid to be the result of a fliult ; ^ 

 and so far as my own observations have gone, I saw nothing in 

 the relations of Culm-measures and Devonian rocks near Newton 

 ^ Paper read before Brit. Assoc, at riymoiitli. 



