A HISTORY OF DEVONSHIRE 



deeper exposure exhibiting over 120 feet of alternating beds of sand and 

 clay and of clay with 27 bands of lignite. At the Potteries near Heath- 

 field station H. B. Woodward' summarizes the section as ' a variable 

 series of grey and white clays, carbonaceous sands, and occasional lignite 

 beds.' ' It was mentioned that a boring had been carried to a depth of 

 520 feet from the surface through clays, sands and lignites without reach- 

 ing the base.' ' An excellent section of the lignite-series with bands of 

 potters' clay ' is visible ' in the " Great Plantation " east of Preston 

 Manor Clay Works.' At Abbrooks gravel is interbedded with the clay. 



Comparing the Bovey lignite flora to the fossil plants in the marine 

 series of the Bournemouth beds, Starkie Gardiner says, * ' when we com- 

 pare the ferns as Osmunda {Pecopteris) lignita, Lastraa bunburyi, the cactus 

 {Palmacites dcsmonorops), the fruits, conifers or dicotyledons, it is seen that 

 by far the larger proportion are not only specifically identical, but occur 

 exactly in the same combinations and manner of preservation.' Reid ' 

 however, pending a re-examination of the Bovey flora, does not regard 

 the botanical evidence as conclusive. De la Beche reconciled the great 

 difference in level between the Greensand said to occur beneath the 

 Bovey clays and that of the Haldons by subsequent disturbance of the 

 beds, or by previous erosion, in either case combined with faults.* 



'At Orleigh Court near Bideford, 43 1 miles from the green sand 

 of the Black Down Hills, and 36 miles from that of Great Haldon,' 

 De la Beche * referred to a patch of sand, ' a few acres in area,' resem- 

 bling the fox mould of the Greensand near Lyme Regis, with ' superin- 

 cumbent gravel ' similar to ' that on the Haldons and Black Downs,' 

 composed of flint and chert in which Galerites albogalerus, Sphatangus 

 coranguinum, etc., were found. About twenty-five years ago no good 

 sections of these deposits were visible ; red earthy clay with chalk flints 

 and broken flints and chips was however exposed, and fragments of in- 

 durated coarse quartzose sand were met with in the vicinity. 



South of Rivaton farm (on a common south-east of Stapledon), 5I 

 miles south-south-east of Orleigh Court, gravel of rather small angular 

 and subangular, and occasional pebbly, quartz, chips and worn nodular 

 pieces of blackish, red, and brown flint, with angular and subangular 

 Culm grit stones in a sand of similar derivation, occurs at 500 feet above 

 the sea, on the summit level of the Culm Measures of the vicinity. The 

 Petrockstow depression (between Torrington and Hatherleigh) lies z\ 

 miles east of this gravel. This depression is 4I miles in length from 

 N. 30° W. to S. 30° E., and about three-quarters of a mile broad, but 

 narrowing northward. The flattish surface consists of a Head of clay 

 with slightly worn fragments of Culm grits and quartz and gravelly 

 seams, from 5 to 10 feet thick ; beneath this stiff unctuous white clay 



' Proc. Geo/. Assoc, for 1900, pp. 426, 427. 



* ^art. Joum. Geol. Soc. 1879^ p. 227. 

 ^ Reid, op. cit. p. 236. 



* Op. cit. p. 236. See also Geolopcal Manual, p. 200. 

 ^ De la Beche, op. cit. pp. 236, 249. 



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