2S4 PEOF. J. PRESTWICH ON THE PvAISED 



overlying irregular gravel. Mr. Maw found no shells in the clay, 

 but only some " blar^kened pieces of driftwood." 



There is not, however, sufficient evidence to connect this deposit 

 with the true Boulder Clay. It is covered by an irregular bed of 

 angular gravel 3 to 8 feet thick, composed chiefly of fragments of 

 grey limestone, and apparently contemporaneous with the Head over 

 the Raised Beach of Barnstaple Bay. This clay would therefore seem 

 to be on the same horizon as the Caves and Blown Sands, and it 

 may be a lake-deposit of that period. It must have had a larger 

 extension than at present, but suffered erosion at the time it was 

 covered by the Head. It requires, however, further examination. 



The well-known Raised Beach of Barnstaple Bay extends, with 

 few interruptions, from Croyde Bay by Baggy Point to Morthoe. 

 There is little to add to the description of it by Murchison and 

 Sedgwick and other geologists,^ except to notice that the sands 

 underlying the Head, which they associated with the Beach, are 

 blown sands or old dunes driven in from the shore after the uplift of 

 the old Beach. The list of shells in the Beach has also been con- 

 siderably enlarged. The clitf-section may be divided into three 

 parts. — The upper one consists of the usual local angular rubble, 

 composed of small and large fragments of slaty Devonian rocks in a 

 brown earth, without apparent bedding, and varies from 10 to 50 

 feet or more in thickness (a, fig. 9, p. 285). It is cemented in places 

 by a calcareous infiltration, forming a dark compact breccia. The 

 Head rests on an irregular indented surface of the Sands, h, which 

 vary in thickness from 5 to 30 feet, and contain occasional thin 

 layers of small subangular fragments of slate. The bedding is hori- 

 zontal, with frequent oblique lamination. Sometimes the Sands are 

 partly, and at other times nearly wholly concreted, as at Baggy Poiiit, 

 where they form a solid overhanging mass. A section of them, under 

 the Head a (fig. 9), there gave : — 



f(^et 



(1. Loose sand, without shells 2 



I 2. Concreted sand 0^ 



7 J 3. Loose sands, with land-shells 2 



} 4. Concreted sand, with land-shells 12 



I 5. Loose sands, with an occasional weathered valve of Mi/tilus 

 \ and Cardimn 8 



The land-shells were numerous in places and were found by 

 Gwyn Jeffreys to belong to Belix virgaM, Da Costa, IT. caiiiiana^ 

 Mont., and Bulimus ventivcosus, Drap. The Bulimus is a South 

 European species, its most northern habitat being the south-west 

 coast of France. The Helices are species still living in the district. 

 On the adjacent recent dunes, HelLv virgata, H. cantiaua, and 

 Bulimus acutus are common. 



These Sands overlie a Beach (c, fig. 9) which consists of worn and 

 rounded fragments of slate, hard grey and micaceous sandstones, 

 chalk-ilints, and pebbles of white quartz and reddish quartzite, in a 



^ Trans. Geol. Soc. 2nd ser. vol. v. (1837) p. 279. Pengelly, Trans. Devon 

 Assoc, for 1867, vol. ii. p. 43. 



