l6o PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



great series and have been assigned to the ' New Eed Sandstone ' 

 or Trias. This is the classification adopted on the published maps 

 of the ^reological Survey. On the other hand, various able observers 

 have pointed out the obvious resemblance of the coarse breccias at 

 the bottom of the series to recognized Permian breccias in the centre 

 of England and to the typical Eothliegende of Germany. I need 

 only refer to the strongly expressed views of Murchison, who, in 

 his ' Siluria,' stated that he " entirely agreed with Conybeare and 

 Buckland, who after a journey in G-ermany in 1816, distinctly 

 identified the Heavitree Conglomerate near Exeter with the Roth- 

 liegende of the Germans." ^ I do not pretend to bring forward any 

 additional evidence or argument that would help to settle this 

 disputed question. My own inclination is to regard the rocks as 

 probably Permian, and to follow Murchison in looking upon their 

 associated igneous masses as furnishing additional reason for 

 assigning them to that stratigraphical position.^ 



No proper account has yet been written of the volcanic group to 

 which I now refer. De la Beche was, I think, the first to recognize 

 the true volcanic nature of the rocks and their contemporaneous 

 interstratification in the red sandstones.^ As traced on the Geolo- 

 gical Survey maps these rocks lie at or near the base of the red sedi- 

 mentary deposits, resting sometimes directly on the Culm Measures, 

 sometimes on an intervening layer of red strata. They include 

 various lavas, often strongly amygdaloidal and vesicular, and also 

 red gravelly tuffs and volcanic conglomerates which are regularlj'' 

 banded with the red sandstones. No petrographical description 

 of these rocks, so far as I am aware, has yet appeared.'* I have 



^ ' Siluria,' 4th edit. (1867) p. 333. See also Berger, Trans. Geol. Soc. vol. i. 

 (1811) pp. 98-102 ; Conybeare and Phillips, ' Geology of England and Wales,' 

 p. 313, footnote ; De la Beche, ' Eeport on the Geology of Cornwall, Devon, and 

 W. Somerset,' chap. vii. p. 193. The subject has been discussed more recently 

 by Messrs. Hull and Irving, who follow the view of Murchison. 



^ Murchison cogently argued that as no signs of volcanic activity were known 

 in the Trias, but were abundant in the Permian system, the Devonshire rocks 

 might be regarded as appertaining to the older series. Op. cit. Triassic vol- 

 canic rocks, however, are now well known on the Continent. 



^ De la Beche quotes J. J. Conybeare as pointing out the intimate connexion 

 of these igneous and stratified rocks (' Annals of Philosophy,' 2nd ser. vol. ii. 

 (1821) p. 165) ; but this author wrote at the time of the plutonist and neptunist 

 controversy, and does not commit himself to any distinct expression of opinion 

 on the subject. 



* An outline of some of their characters will be found in a paper by Mr. W. 

 Vicary in Trans. Devonshire Assoc. 1865, vol. i. part iv. p. 43. 



