Middle 

 Culm Measures. 



> MR. E. A. NEWELL ARBER ON THE UPPER [Feb. I907, 



Upper f f -^ ar( ^ rather thick, evenly-bedded 



Culm Measures. \ E gS esford Grits, j g re J S rits > with shales and slat r 

 [ I beds. 



( f Thickly & thinly-bedded, greenish- 



grey and reddish, much jointed 

 Tivertonand Mor- sandstones, associated with ovoid- 



chard Types, and \ p a Wl^ng shales 

 Ugbrooke Types. ] Bather thick, grey shales with hard, 

 fe " ne ' coarse » anc i locally-conglo- 



meratic sandstones, irregular in 

 1 association. 



( Interbedded, hard, thin, brown- 

 Exeter Type. weathered grits and splintery or 

 broken grey shales (probably a 

 [_ local type). 



I have recognized both the Eggesford and the Morchard types in 

 various localities ; but I believe them to be simply local variations, 

 and not definite litbological facies constant over wide areas, thus 

 clearly distinguishing a higher from a lower horizon. 



This conclusion is also in accordance with De la Beche's l obser- 

 vations. He remarks that 



'notwithstanding the size of the area in which they are comprised, the uni- 

 formity of the larger part of the carbonaceous rocks, viewed generally, is one 

 of the most remarkable circumstances connected with them, and from which 

 we may infer considerable uniformity in the general conditions under which 

 their constituent mud, silt, sands, and vegetable remains have been accumulated/ 



I have not observed any typical grits or slates among these Upper 

 Carboniferous rocks, although others speak of such as occurring. 

 The sandstones appear, so far as superficial observation is concerned, 

 to be generally of a fine texture. McMahon 2 came to the same 

 conclusion from a study of the rocks near Bude. He speaks of 

 them as being ' very fine-grained rocks,' and adds that 



1 some are distinctly arenaceous, and may be called fine-grained earthy sand- 

 stones ; but they pass gradually into argillaceous shales.' 



Numerous quartz-veins are often conspicuous in the sandstones, 

 as was already noticed by Sedgwick & Murchison. 3 They appear, 

 however, to be much more frequent in the rocks to the south of 

 Hartland Point, and in Cornwall. 



The shales met with in different parts of the coast-line vary con- 

 siderably in their petrological and physical characters. One may 

 distinguish several impersistent types, of which the black splintery 

 and the ovoidally-splittiDg shales are among the more abundant. 

 I have not seen any rocks that show signs of true cleavage, and 

 McMahon 4 also apparently failed to discover any true slates. 



As is well known, the Upper Carboniferous rocks are highly 

 tilted and folded, and often bent or contorted. Faulting is very 

 common, and is clearly seen in the coast-section, where overthrust- 

 planes are also much in evidence in several localities. Gentle 



1 De la Beche (39) p. 123. 



2 McMahon (90) pp. 180-109 ; see also Sedgwick & Murchison (40) p. 677. 

 s Sedgwick & Murchison (40) p. 678. 



McMahon (90) p. 109 ; see also Sedgwick & Murchison (40) p. 679. 



