British Association. 37^ 



silicious masses alternate with slates, and are in some places sur- 

 mounted by great masses of red unctuous shale, which, when in 

 a more solid form, generally exhibit a cleavage oblique to the 

 stratification. 



5. The Silurian System, resting conformably on the preceding, 

 of great thickness, on the western coast of North Devon, occupying 

 a zone several miles wide, and containing many subordinate beds and 

 masses of lime-stone. In its range towards the eastern part of the 

 county, it gradually thins off, but its characters are well preserved, 

 and throughout it contains an incredible number of characteristic 

 organic remains. 



6. The carbonaceous system of Devonshire. This system is very 

 greatly expanded, stretching in a direction east and west across the 

 county, occupying the whole coast from the neiglibourhood of Barn- 

 staple to St. Gennis, in Cornwall, and on its southern boundary 

 ranging so close to Dartmoor, that its lower beds have been tilted up 

 and mineralized by the action of the granite. This great formation, 

 is, therefore, deposited in a trough, the northern border of which 

 rests partly in a conformable position upon the Silurian system, and 

 partly upon older rocks, partly of the division, No. 4. Its southern 

 border rests on the slate rocks of Cornwall and Launceston, and on 

 the north flank of Dartmoor. From one side to the other, it exhi- 

 bits an extraordinary succession of violent contortions, but its true 

 place in the ascending section, admits of no doubt whatever. In 

 some places, it is overlaid by patches of green sand, and in one part 

 of the coast, west of Bideford, it is overlaid by the conglomerates of 

 the new red sand-stone, which are seen for half a mile resting un- 

 conformably on its edge. The lowest portion of this vast deposit is 

 generally thin-bedded, sometimes composed of sand-stone and slate, 

 with impressions of plants— sometimes of indurated compact slate, 

 both in an earthy and crystalline state. These beds are surmounted 

 by alternations of shale and dark-coloured lime-stone, with a few 

 fossils. Subordinate to these beds, there are on the west side of the 

 county many thin veins and flakes of culm and anthracite. 



On the eastern side of the county the coal is wanting, and the cal- 

 careous beds are much more expanded. On the south side of the 

 great trough, the calcareous bands and dark shales are well exhibited, 

 but near Oakham j)ton are, as above stated, mineralized by the action 

 of the granite. The higher beds of this deposit are well exhibited 

 on the coast west of Bideford, and consist of innumerable alternations 

 of ferruginous sand-stone, flag-stone, and shale, containing in several 

 places concretions of iron-stone, very often exhibiting impressions of 

 plants ; and one extended tract of country, containing at least three 

 beds of culm or stone coal, associated with shales, contains many 

 plants of species not known in the true coal measures. Though in 

 a state of greater induration than the ordinary coal measures of ling- 

 land, and in most })arts almost destitute of any trace of coal, yet 

 even in these respects, it differs not from a great unproductive tract 

 of the coal-field of Pembrokeshire. 



Wednesdai/ , 24th AuyKst. — Mr. Stutchbury read a paper on 

 some newly discovered Saurian remains, from the muguesian oonglo- 



