394 Mackintosh — Railway Geology in Devon. 



Tracey, the geologist enters on controverted ground. There is 

 perhaps no spot of equal dimensions in Britain on wliich more has 

 been written, and less understood, The origin of the Bovey forma- 

 tion is still the great enigma of Tertiary geology. The railway 

 sections between Newton and Bovey seldom or ever penetrate 

 beneath the " head " into the body of the formation, but the coal- 

 pit can be soon reached from the Bovey station. There the reader 

 can form his own opinions about the mode of accumulation of the 

 beds. It will be seen from the foregoing statements that the only 

 fact supposed to prove their lacustrine origin is the occurrence of 

 freshwater seeds, which (as nothing in the formation is in situ) may 

 have been drifted into a saltwater estuary or creek from a freshwater 

 habitat. The facts and considerations which seem to favour the 

 marine or, at least, the fluvio-marine origin of the Bovey beds, 

 partly observed by the author, and partly selected from the papers 

 above noticed, may be briefly stated as follows : — The supposed 

 barrier in the area of the present Teign estuary, necessary to dam 

 up a lake, must have been, at least, 200 feet high (taking the height 

 of the surface at the coal pit at about 100 feet above the sea, and 

 allowing a denudation of 100 feet indicated by the fault), and it is 

 highly probable that the Bovey beds once reached a height requir- 

 ing a much higher barrier. It is, however, unreasonable to suppose 

 that the Teign estuary valley was filled up to such a height in or 

 since middle Tertiary times. The slopes of this valley down to the 

 water's edge (excepting where there are small cliffs) are obviously a 

 continuation of the general contour of the surface of the neighbour- 

 hood, including the sides of the Bovey basin, and must have been 

 formed by a pre-Miocene denudation. As regards the "head," the 

 occurrence of boulder-stones (I have seen some on the side of Lever- 

 ton road four feet in diameter) , and other facts, show that it could 

 not have been accumulated by any motion of water in a tranquil lake. 

 The highest P^oZas-borings near Torquay must have been made when 



been worked about 90ft. deep. Traces of clay may be found as far in the direction of 

 Torquay as the Old Atmospheric Engine House. At the Bovey Pottery (coal-pit) the 

 beds dip to S.E. about llin. in a fathom (an old man who has worked among the beds 

 nearly 40 years informed the author that about the Pottery they nowhere dip in any 

 direction but S.W). Mr. Key gives a section taken by the late justly lamented Dr. 

 Croker, of Bovey, in which some of the beds are represented as very unequal in thick- 

 ness and of variable dip. Others have their abrupt ends apparently resting on beds 

 less inclined, while an immense basin denuded out of the beds is filled with "head." 

 Mr. Key believes that the Bovey deposit, both body and head, originated in the river 

 Bovey, discharging various kinds of sediment into a deep lake. The river once ran 

 through the lake from near Bovey to near Newton, and thence, by way of Torr, to 

 Torbay — the estuary of the Teign having been subsequently excavated. — Dr. Heer 

 (paper read before Royal Society, November, 1861) states that the dwarf birch found 

 in the "head" is an arctic plant, and, along with the associated willows, points to a 

 cold climate. In the body of the deposit the following sub-tropical plants of Lower 

 Miocene Tertiary age have been classified : — Cinnamon, laurels, fig, palm, tree-ferns, 

 etc. But the woods that mainly furnished the lignite consisted of a huge sub-tropical 

 coniferous tree. Sequoia Couttsim, resembling the present Sequoia of California. The 

 lower lignite beds consist almost entirely of stems of this and other trees, with brownish 

 black clay. The trees never occur upright, and must have been drifted, the majority 

 from a distance beyond the shores of the lake in which the beds were accumulated. 

 The occurrence of seeds of Nymphcea shows that it must have been a freshwater lake. 



