BEACH AXD BOULDERS XEAR BEAUXTOX AXD CROTDE. 



665 



jagged ridges of the rock just in front of a small alcove or cave in 

 the western face of a portion of the sandstone cliff which runs out 

 south from the hill. It measures about 4 feet across from corner 



Fig. 5. — Boulder of Grey Porphyry at base of Cliff South of Saunton 

 Down, North end of Barnstaple Bay (April 11, 1887). (Scale 

 ~\ feet to 1 inch.) 



a. Eecent shingle. d. Pilton Beds. 



b. Boulder of grey porphyry in 1 foot of water. 



c. Consolidated blown sand, modified at base by action of sea, with lines of 



shingle and sea-shells, and alternating in upper part with talus. 



to corner of the irregular rhomboidal mass now exposed. On the 

 south side of it a fold over of one of the harder beds has caused a 

 stronger barrier than usual and probably determined the position in 

 which it rested. 



This boulder consists of a grey porphyry much resembling that 

 so common on Arenig ; but I should be sorry to say that it could 

 not have come from the felsite which occurs at intervals for many 

 miles at the base of the Pickwell-Down Sandstone, as that is ex- 

 posed only here and there, and, where seen, is so variable that we 

 may easily allow that there may be parts of it very like the Saun- 

 ton boulder. 



The third boulder (fig. 6) is more like the Ross-of-Mull granite 

 than any other with which I am acquainted. It occurs in a cave 

 eaten out by the waves in the very base of the sand-cliff, a short 

 distance further east than that last described. It rises out of some 

 newly tossed-up shingle, and supports the roof of the cave. From 

 the levels observed outside, it is clear that it must rest on the solid 

 rock. It is partly concealed by the shingle, so that exact measure- 

 ments cannot be obtained. From what was exposed when Mr. 

 Townshend Hall saw it he estimated that it must weigh between 

 10 and 12 tons. 



Mr. Townshend Hall * thinks £; it is very doubtful whether there 



* See note t on p. 666. 



Q. J. G. S. ISo. 172. 2 z 



