306 Geological Society : Prof. Sedgwick on the 



conflicting evidence be discovered) the culm measures and common 

 coal measures must continue to be placed on the same parallel. 



Lastlj', he states that, independently of any question of classifica- 

 tion, the former paper by Mr. Murchison and himself first pointed 

 out the following facts in the general structure of the county : — 



(1.) That the Wavellite rock and culm limestone (of Barnstaple, 

 &c.) were in position, structure, and fossils distinct from all the other 

 calcareous groups of Devon. 



(2.) That the same group was repeated over again with a reversed 

 dip on the north side of Dartmoor, and entirely distinct from the calca- 

 reous slates of Cornwall, with which it had no analogy in structure 

 or fossils. 



(3.) That the Holcombe Rogus limestone was a part of the culm 

 series. 



(4.) That the culmiferous system was superior to all the slate rocks 

 of Devonshire and Cornwall, and was overlaid by no older rock than 

 the new red sandstone. Whereas before, the portion of the culm 

 series near the granite had, from its metamorphic structure, been 

 confounded with the oldest rocks of Devonshire and Cornwall ; and 

 the position of whole series among the Devonian groups had been 

 misapprehended. 



III. South Devon section. — This section, in conformity with the 

 scheme given in the former paper, is as follows, in the ascending 

 order* : — 



(1.) A series of slate rocks subdivided into two groups, — the lowei 

 containing a few calcareous bands, the upper group more calcareous 

 and ending with the Plymouth limestone. The two are considered 

 as one formation ; and the name, Ashburton bands, which had been 

 given to the calcareous beds of the lower division, is now withdrawn, 

 as the position of the Ashburton lime rock is considered ambiguous. 

 The name of Ugborough bands is not liable to the same objection. 



(2.) A great group of coarse red flagstone and slate, identical in its 

 structure with No. 3. of the North Devon section, and containing 

 some corals that do not appear in the mountain limestone, but are 

 found both in the Cambrian and Silurian systems. This group is 

 provisionally identified with No. 3, of the North Devon section. 



(3.) A great group of slate rocks without beds of limestone, and 

 very rarely with any traces of organic remains. By the suppression 

 of No. 4., this group is considered as the equivalent of No. 5. of 

 the North Devon section. 



(4.) Mica and chlorite slate, anomalous in structure and position, 

 and forming no part of the ascending series. 



The preceding identifications are only provisional, and many desi- 

 derata are enumerated ; but it is considered certain that the South 

 Devon section belongs, on the whole, to a lower series than the 

 North Devon. Neither of them are, however, supposed to descend 

 lower than the Upper Cambrian, or the higher part of the Lower 

 Cambrian, group. To place the South Devon section above the North 



* See Proceedings, vol. ii. p. 5G2. [or L. & E. Phil. Mag. vol. xi. p. 

 310,317.] 



