Bernard Hohson — Permian Breccias of 8. Devon Coast. 311 



I. — The Size of the Tkansported Blocks. 



Sir H. de la Beche,^ describing the Red Sandstone Series, says : 

 " On the side of Little Haldon Hill there are blocks of quartziferous 

 porphyry of more than a ton in weight." 



Mr. W. Pengelly^ says: "Again, the trappean masses are not 

 unfrequently of great size. The largest probably occur near the 

 month of the Teign, especially in the cliff between Shaldon and the 

 Ness Point. They are more or less ellipsoidal in form, and sometimes 

 measure fully five feet in greatest diameter." 



The late Mr, E. N. Worth ^ says: "We have another valuable 

 hint [of their local character] in the fact that these fragments attain 

 their largest size in the vicinity of Teignmouth, and that thence 

 both to the north and south they rapidly graduate downward to very 

 moderate dimensions, and, in fact, into sand. . . . Especially 

 prominent also are the boulders in the Dawlish valley. Blocks 

 occur ranging to four and five feet in diameter." 



In order to facilitate reference I have arranged the descriptions 

 of exposures examined in regular order, beginning at the south and 

 proceeding along the coast northwards. 



The chief points to be brought out are : — 



(1) The size of the largest blocks observed. 



(2) The fact that they often occur amid blocks (not matrix) of 

 much smaller average size. 



(3) The point referred to by Mr. R. N. Worth that the fragments 

 (particularly of quartz-porphyry) are largest between Bundle Head 

 and the Ness near Teignmouth, and diminish in size both to the 

 north and south. 



(4) That the Devonian limestone fragments, abundant (in most 

 cases) to south are comparatively scarce to north of Teignmouth. 



In describing the average size of the fragments in the breccia the 

 matrix, which is present in all cases, is left out of account. 



1. Eoundham Head, near Paignton} 

 At the shore end of the south side of Eoundham Head is a very 

 excellent exposure in the cliff, estimated at 50 feet in height. The 

 upper three-eighths of the cliff face consist of breccia, which overlies a 

 bed of rock-sand about half the total height in thickness and showing 

 very clear current-bedding.^ It in turn overlies another bed of 

 breccia, and the whole series is thrown down to the west by a fault 

 exposed with diagrammatic clearness.*' This is perhaps the most 

 convincing exposure I saw, proving deposit by water. At this spot 

 the breccia is not coarse. Most of the fragments are from one to four 



1 " Report ou the Geology of Coruwall, Devon, and West Somerset," 1839, p. 204. 



' " The Red Sandstones, Conglomerates, and Marls of Devonshire," pt. ii : Ann. 

 Rept. and Trans. PljTnouth Inst., 1862-3, p. 30. 



3 " The Igneous Constituents of the Triassic Breccias and Conglomerates of South 

 Devon" : Quart. Journ. Geol. Soc, 1890, pp. 71, 72. 



* See Plate XXI, Fig. 1. 



» Pen<relly describes and figures false bedding at Slapton, Start Bay, and Goodrington 

 Sands, Torbay: Trans. Plj-mouth Inst., 1862-3, p. 31. 



6 See AV. A. E. Ussher, Geol. of Torquay : Geol. Survey Mem., 1903, pp. 110, 111. 



