316 JJcniard Jlobnon — renniaii Breccias of S. Decon Coast. 



35 ft. above it nnother inaccessible block of rook over 1 It. in diameter. 

 All these blocks lie jmniUol to the boildiujij-planos, wliicli have au 

 n|)paront dip of 20' north wanls. No ovidoiioo of a boulder dropped 

 by ice and bonding down the lamina* below it, as described by 

 Trofessor Janios (Jeikie' as oocurrinii; near Uddingston, Lanarkshire, 

 was anywhere seen. At the 1j08.| mile post (Q.W.U.) several 

 fragments of limestone, one of them 11 inches long, elliptical, fairly 

 well rounded, occur in the breccia; and 4 paces north of the 

 llOT'i mile-post limestotie fragments up to (! inches long ooour in the 

 breccia, which is here coarser than it is nearer Teignmouth. At 

 124 paces north of tlie UOS mile-post a block of reddish quartz- 

 ]>orpliyry 2 ft. by 1ft. Sin. ooonrs ; north of the 207^' mile-post 

 at 12 paces is a boulder of typical red quartz-porphyry 1 ft. 4 in. by 

 H in. ; at l.'JO paces a ((pmrtz- porphyry) block \\ h. by 2 ft. by 

 1ft. Oin. +; at 243 paces a ((juartz- porphyry) block 2 ft. 2 in. 

 by 1 ft. All these tbin- blocks are in the breccia. At the north end 

 of Parson's 'i'unnel (the iirst north of Teignmouth) fragments of red 

 <piarf/,-porjihyry, (piartz-porphyry with greenish groundmass, grey 

 (piartzite, weathering purplissh, and limestone occur in the breccia. 

 At the south imuI of the secoiid tuimel from Teignmouth (12i) paces 

 north of the 207 mile-post) the breccia is not at all coarse; most of 

 the fragujents are not more than 2 inches, a few 4 inches, and in rare 

 cases () inches across. Just north of Dawlish station at the 200 mile- 

 post the rocik consists of alternating beds of red sandstone and breccia, 

 each 4 inches to a feet thick. The breccia consists of small angular 

 fragments, mostly 1 incli in diameter or less, but a few o to 5 inches 

 across. 



II. — Thk Ouioin ok 'I'liifi Quahtz-i'oki'hyky Hi.ooks. 



The late ]\lr. Iv. N. Worth has decribed -' the red ipuutz- porphyry 

 80 common in tlie breccia as a " Deep-red porphyritic rock, varying 

 to red brown and purplisli brown ; compact lelsitic base with 

 }>orphyritic quartz and felspar, some of the latter kaolinized, some 

 IMurchisonite ; occasionally, but not invariably, st)mo nuca. This is 

 the so-called red ' jjorpliyritio trap * more or loss characteristic of 

 the conglomerates within our area, from Torbay to the Crediton 

 valley, and the origin of whicli has been a special topic of discussion. 

 Save in colour, lu)wever, those fragments are hardly distinguishable 

 from some Dartmoor elvans." A microscopical section which 1 have 

 had made from a block, which measures 1 ft. 4 in. by i)i in. by 5 in. -f 

 and still remains embedded in the conglomerate, at the Ness opposite 

 Teignmouth, shows phenocrysts t)f (puirtz, felspar, brown mica, and 

 apatite. The felspar consists ehieily of much altered large porphyritic 

 crystals witlu>ut any visible twinning himelhe, and of much scarcer, 

 smaller, and fresher porphyritic crystals of lath-sliaped form, also 

 not visibly twinned. The mica phenocrysts are sometimes inclosed 

 in the larger felspars. The groimd-mass appears by rellected light 

 reddish, by transmitted light brownish, owing to ferruginous matter. 



' '• Tlu' Groat Ico Ago," Srd od. (1S94), p. JTt. 

 • Quiut. Jouru. Uooi. Soc, 181)0, p. 75, item 29. 



