PvOCKS OF SOUTH DEYON. 493 



ground that, whilst the lower beds of the Culm- measures were 

 equally well developed in North and South Devon, the upper beds 

 of the Devonian did not correspond ; and even in South Devon and 

 East Cornwall the Culm-rocks appeared to rest upon Devonian 

 strata of different ages. 



I have elsewhere given reasons * for regarding the Petherwin 

 beds and those of Druid, near Ashburton, as probably contempora- 

 neous with the jRliynehonella-letiensis-zone of the "Pammenien" of 

 the Ardennes, but beyond this I have been unable to extend the 

 comparison to that region ; the Cypridinen-Schiefer mainly consti- 

 tuting the upper part of the Devonian in the district under descrip- 

 tion proves, as Dr. Kayser has shown, a correlation rather with the 

 German than the Franco-Belgian Upper-Devonian type. 



In 1887 I discovered Upper-Devonian slates in the Culm-measure 

 area between Bickington and Bovey Tracey ; these consist of grey 

 slates and grey and brown mudstones, somewhat recalling the 

 Druid beds, and of red and greenish slates of the normal type of 

 the Cypridinen-Schiefer. In the only places where unfaulted 

 junction-relations with the Culm-measures are visible, no uncon- 

 formity is apparent. Coddon-hill beds (identified as phthanites by 

 Professor Gosselet) seem to overlie the Knollen-Kalk and Cypridinen- 

 Schiefer by the path-road to Lewell, near Chudleigh. This junction 

 appeared to Prof. Kayser to be a natural one ; whilst M. Gosselet 

 regarded it as a proof of unconformity. The subsequent experience 

 I have acquired does not enable me to decide authoritatively 

 between these views ; but the acceptance of a natural junction in 

 this spot is not in accordance with the development of the Upper- 

 Devonian slates in the South-Devon area. 



We may conclude generally that the Upper- Devonian slate 

 and psammite type of North Devon gave place southward to a 

 purely slate type ; and that the latter, probably from unequal rate 

 of deposition in deeper water, attenuated as the distance from 

 the shoal-areas increased ; but, as the conditions which produced 

 similar sedimentation in the earliest Culm-rocks of ISTorth and 

 South Devon would probably be the same, it is not unlikely 

 that their production in South Devon precluded the equivalent 

 representation of the upper part of the Devonian series, and even 

 occasioned an overlap of the Culm-measures. 



I purpose to lay before the Society the evidence for the grouping 

 of the Devonian rocks of South Devon under the following heads : — 



I Cypridinen-Schiefer (Entomis-slates). 



Upper Devonian I Goniatite-limestones and slates. 



[ Massive limestones. 



I Middle Devonian Limestones. 



Middle Devonian \ Ashprington volcanic series. 



I Eifelian slates and shalj limestones. 



Lower Devonian Torquay area, Paignton area. 



* Trans. Devon. Assoc, for 1889. 



