Proceedings of the British Association. 351 



this series are very few organic remains. It is several feet in thick- 

 ness, occupying the whole coast from the west end of the Valley of 

 Rocks to Combe Martin. — 3. The calcareous slates of Combe Mar- 

 tin and Ilfracombe, of very great aggregate thickness, abounding in 

 organic remains, and containing in a part of their range at least nine 

 distinct ribs of limestone burnt for use. This limestone is prolonged 

 into Somersetshire, and appears to be the equivalent of that on the 

 flanks of the Quantock Hills. — 4. A formation of greenish and lead- 

 colored roofing slate of great thickness, and occupying a well defined 

 zone in North Devon, its upper bed alternating with and gradually 

 passing into a great deposit of sandstones of various colors and mica- 

 ceous flagstones. These siliceous masses alternate with incoherent 

 slates, and are in some places surmounted by great masses of red unc- 

 tuous shale, which, when in a more solid form, generally exhibit cleav- 

 age oblique to the stratification. — 5. The Silurian system resting 

 conformably on the preceding, and of great thickness, on the north- 

 western coast, containing many subordinate beds and masses of lime- 

 stone. In its range towards the eastern part of the county, it grad- 

 ually thins off, but its characters are well preserved, and it every 

 where contains vast numbers of characteristic organic remains. — 

 6. The carbonaceous system of Devonshire, in a direction east and 

 west across the county, in its southern boundary so close to Dartmoor 

 that its lower beds have been tilted up and altered by the granite. 

 It occupies a trough, the northern border of which rests, partly in a 

 conformable position upon the Silurian system, and partly upon older 

 rocks, probably of the division No. 4. Its southern border also rests 

 on the slate rocks of Launceston. It every where exhibits a suc- 

 cession of violent contortions. In some places it is overlaid by 

 patches of green sand, and west of Bideford by conglomerates of 

 the new ried sandstone. The lowest portion of this vast deposit is 

 generally thin bedded, sometimes composed of sandstone and shale, 

 with impressions of plants, sometimes of indurated compact slate, 

 containing wavellite. These beds are surmounted by alternations of 

 shale and dark colored limestone with a kw fossils. Subordinate to 

 these, there are on the western side of the county thin veins and 

 flakes of culm or anthracite ; but this is wanting on the eastern side, 

 and the calcareous beds are more expanded. The higher beds of 

 this deposit are well exhibited on the coast west of Bideford. These 

 often contain impressions of vegetables. Though in a state of greater 

 induration than the ordinary coal measures of England, and even 'm 



