Mackintosh — Railway Geology in Devon. 391 



flints. On the north and south sides of Dawlish Valley, near the sea- 

 coast, there is a great thickness of gravel, which, at one time, may 

 have extended continuously across. But to see the most instructive 

 and easily-accessible sections of flint-gravel requires one to walk from 

 Dawlish to Teignmouth along the old turnpike road, which cuts 

 deep into the ridges by which the nearly parallel east and west 

 valleys are separated. These cuttings expose Triassic sand, sandstone, 

 and conglomerate, capped with flints mixed with re-assorted Triassic 

 pebbles. In some places, beneath a layer of flint-gravel, there are 

 detached flints deeply imbedded in curved, contorted, and oblique 

 laminas of sand. One section reveals flints and pebbles more or less 

 stratified beneath re-deposited and finely-laminated Triassic sand (PL 

 X'^mi. Fig. 1, a laminated sand, h layers of light-coloured sand, c 

 flints and pebbles, d Trias). Another section shows a mass of sand 

 enclosing a patch of flint-gravel, and covered with re-arranged Triassic 

 shingle and flints, the lower parts stratified. It is clearly impossible 

 to explain the interweaving of flint-gravel with Triassic sand and 

 shingle displayed in the above sections, without having recourse to 

 marine currents, possibly laden with icebergs. Eain will not account 

 for it ; and its situation, on or near the tops of ridges, precludes our 

 referring it to streams or rivers. To the south of the valley which 

 opens on the coast at the " Parson and Clerk " promontory, I could see 

 no trace of flints, nor anywhere between there and Bishopsteignton ; 

 an important fact showing that the flints are not the mere down- 

 lettings of a former gravel-covering, co-extensive with the Chalk, all 

 the softer matter above the Trias having been washed away by rain.^ 

 This absence of flints from considerable spaces seems to indicate a 

 sweeping denudation by locally-directed or locally-intensified cur- 

 rents which left flints on certain areas, and cleared them away from 

 others. 



lAltle Haldon. — Every geologist who travels by the South Devon 

 Railway should walk from Dawlish (two miles) or Teignmouth (one 

 mile and a half) to the top of Little Haldon, which is about 800 

 feet above the sea-level. On looking north from the high ground 

 to the north of West Teignmouth church, this hill, with the spur it 

 sends off towards the east, presents the outline seen in PI. XVIII. 

 Fig. 2, in which a is Trias, b Greensand and sandstone, c Flint-gravel. 

 At d and e no flints could be seen. At / there were two rounded 

 trap boulders (amygdaloid passing into a kind of porphyry) be- 

 tween two and three feet in diameter. Between Little Haldon and 

 Teignmouth cemetery many trap boulders may be seen on the road- 

 side. I could find no indications in this district of any rocks in situ 

 between Trias and Greensand. The main hill (Little Haldon) pre- 

 sents a curved surface when viewed from the south, but in a direction 

 north and south it is a perfectly level line, which, at a distance, 

 excites the wonder of the beholder. On the sides of the hill I 

 examined several pits, in which the gravel was at least ten feet 

 thick. It consisted of flint and chert fragments more or less rounded, 



1 Sir H. de la Beche long ago noticed the absence of flints from large areas lying 

 between flint-strewn surfaces as a difliculty in the way of the atmospheric theory. 



