A. J. Jukes-Browne — The Bovey Deposits. 261 



me it is evident that the results are sure to be interesting, and that 

 much new botanic material will be obtained. 



Until quite recently it has been very generally supposed that the 

 Bovey Basin was a natural lake-basin, and that its present limits were 

 not far within the limits of the original lacustrine area. I have, 

 however, little doubt that the existing basin in which the deposits lie 

 is a tectonic basin, and not in any sense an actual lake-basin. The 

 high dips to the north-east, which are observable on the south-western 

 border of the basin, as at Staple Hill, and which are opposed to 

 the more moderate dips seen at Heathfield and Preston, are sufficient 

 to prove the nature of the syncline. 



The Bovey Basin may, in fact, be compared with that of Orglandes 

 near Valogne in the Cotentin, in which marine Eocene and Oligocene 

 beds occur in the form of an outlier separated from the main tract 

 of the Paris Basin. If the Bovey Basin had been filled with marine 

 Bracklesham and Barton Beds, no one would have thought of supposing 

 it to be anything else than a tectonic basin formed by subsequent 

 flexure of the crust. It is only the fact of its contents being entirely 

 of freshwater and terrestrial nature that has perpetuated the very 

 natural mistake which was made by the earlier geologists. 



As already remarked, the succession of deposits proved at Heathfield 

 is somewhat remarkable, and the order in which they occur is not 

 what would have been expected if the deposits had all been formed 

 beneath the waters of an ordinary lake. If the Bovey Basin had been 

 part of a lake fed by one or more copious rivers, and if the lignites 

 had been formed by masses of driftwood carried down by these streams 

 during periodical floods, one would have expected the resulting deposits 

 to be an alternating series of sands, clays, and lignites throughout the 

 whole thickness, or possibly an upward transition from gravel and 

 sand through sands and clays to clays and lignites, and finally to the 

 peat and lignite of a silted-up swamp. Instead of this being the case, 

 we have the lignites in the lower part and the alternating series of 

 sand and clay in the higher part. 



What, then, are the lignites, and how were they formed ? To 

 answer this question we must ascertain what kinds of plants enter 

 into the composition of the lignites. So far as the beds examined by 

 Heer and Pengelly are concerned, they consist of the matted remains of 

 certain trees, ferns, and other plants which seem to have grown and 

 decayed in the place where they now occur. 



I am aware that Heer held a different opinion, but I do not think 

 that the facts which he recorded support the view which he expressed. 

 He wrote as follows' : — " The lignite beds of the under series consist 

 almost entirely of tree-stems (probably belonging in great measure to 

 8ec[uoia Coutsm) ; these alternate with masses of a brownish-black 

 clay, the dusky colour of which has doubtless been produced by the 

 decomposition of the softer portions of the plant. No leaves offer 

 themselves for recognition, but here and there twigs and seeds and 

 little fruits, as Carpolithes Websteri and C. nitens. The tree-stems, 



' The Lignite Formation of Bovey Tracey, 1863, p. '25, reprinted from the Phil. 

 Trans, of 1862, pt. ii. 



