Geology of the South-east of Devonshire. 449 



deposits once extended wherever this breccia now occurs ; for the blocks are so 

 angular that they cannot be supposed to have been conveyed from a distance. The 

 breccia, with its accompanying sandstones, occurs on the Blackdowns ; it is very 

 abundant in the valleys about Sidmouth ; it has been worn into rounded boulders 

 and pebbles in the great valley of the Exe ; it is found again in tabular masses on 

 the Haldons, below the accumulation of more rounded materials (p. 448), and in 

 similar angular blocks beneath the pipeclay, A very large block serves as a foot- 

 bridge over a water-course near Kingsteignton *. 



Secondary Deposits. (Map, PI. XLI. Sect. PI. XLll. Figs. 1, 2, 3, 5, 8 A.) 



§ 1. Chalk. — There are the following proofs that the chalk extended over por- 

 tions of South Devon, from which it has been since removed : 1st, in the abundance 

 of chalk-flints, uninjured by transport or attrition, which crown the greensand hills 

 of Haldon (fig. 8 A.); and 2ndly, in the circumstance that the high lands along 

 the line of coast, from the Exe westward, present a very uniform elevation, the dip 

 of the beds being in the same direction, and at such angles, that, proceeding from 

 west to east, we encounter a constantly ascending series, and find the various 

 divisions smoothed off, as they rise to the general surface-line of the country. 



The chalk in the valley of Beer offers the same artificial divisions which it does in 

 the South Downs, the only difference worth noticing being, that the cretaceous series 

 generally in its extension westward must have presented, when complete, a gradually 

 decreasing thickness. With the slight difference of a rather larger proportion of 

 siliceous particles, the chalk seems to have preserved its general appearance as far 

 westward as the small overlying mass on Maynard Hill, where it is very remarkable 

 on account of its great abundance of the remains of Radiaria. Blocks of chalk may 

 be found among the debris as far west as Peak Hill, near Sidmouth, and the thick 

 capping of angular flints on the greensand of Haldon, as before stated, and on that of 

 the Bovey valley, indicate that the formation once extended thus far. 



Certain white granular beds, worn into deep furrows on the upper surface, which 

 surmount the greensand at Staple Hill, near Stover, and contain the spines of a 

 Cidaris, may perhaps represent chalk. (PI, XLH. fig. 2.) 



§ 2. Greensand. — The greensand of the S.E. parts of Devon may be considered as 

 belonging to the great mass of Blackdown, so well described and illustrated in Dr. 

 Fitton's memoirf . An interesting fact, which appears to have escaped observation, 

 is the occurrence of a shingle bed in the lower part of the deposit, and well seen in 

 the capping of greensand on Salcombe Hill, near Sidmouth. The pebbles consist of 



* See an account of similar blocks in Dorsetshire in the Memoir of Dr. Buckland and Mr. De la 

 Beche on Weymouth, Geol, Trans., 2nd Series, vol. iv. p. 4. 

 t Geol. Trans., 2nd Series, vol. iv. p. 235. 



