G. W. Grahham— Wells of North -Eastern Sudan. 265 



neighbouring sea, it is probable that a succession of lignites and thin 

 clay beds would have been formed which would have greatly resembled 

 those of the lower part of the Bovey Series. 



The history of the Bovey and Newton Abbot district seems therefore 

 to have been as follows. During the earlier part of the Eocene 

 period, the time represented by the Lower or London Eocene strata, 

 the west of England was a land-surface, and eastern Devonshire was 

 covered by a sloping table of Chalk which was being reduced to the 

 condition of a peneplain by subaerial detrition. After the epoch of 

 the London Clay and Bagshot Sands the south of England seems to 

 have sunk slowly but continuously, allowing the shallow bay or 

 estuary of the Bournemouth Beds to spread farther and farther 

 westward ; leading also to the formation of lagoons, lakes, and swamps 

 on the low-lying plains adjoining the rivers which emptied themselves 

 into this bay. 



The Bovey and Newton district would be part of this lake-and- 

 swamp area. We know that the granite of Dartmoor was exposed 

 and lay to the west of it, rising doubtless above the level of the 

 swamp land, but not into high and hilly ground as it does at the 

 present day. There may also have been somewhat higher land to 

 the south of it, so that it probably drained eastward or northward. 

 Hence we see that the local conditions, both physical and climatic, 

 were similar to those which have led to the formation of the Dismal 

 Swamp of Virginia; except that the Bovey district was farther away 

 from the seabord of the period, and that continuous subsidence resulted 

 in the accumulation of much thicker masses of lignitic materials. 



For a long time it would seem that the vegetation was so luxuriant 

 that in spite of the subsidence the Heathtield swamp was always 

 choked with the decaying vegetable matter which has since been 

 consolidated into the lignite beds. There came a time, however, when 

 the swamp was invaded by the waters of an adjoining lake and the 

 forest was buried under a deposit of lacustrine mud ; such invasions 

 became more frequent until at length it was only occasionally that the 

 swampy vegetation could once more establish itself over the same tract 

 of ground. 



Finally, if I have correctly interpreted the succession of beds in the 

 Bovey Series, lacustrine conditions were permanently established, and 

 the only deposits formed were white clays and fine yellow sands, both 

 apparently being materials derived from the detrition of Dartmoor. 

 It seems possible that these may be of Oligocene age, but so far as 

 I know there are no open exposures of them, and a special excavation 

 would have to be made for their exploration. 



IV. — Wells of the North-Easteen Sudan. 



By G. ^y. Gkabham, M.A., F.G.S., Geologist to the Sudan Government. 



rpHE Anglo-Egyptian Sudan territory covers an area of about a 

 \_ million square miles, throughout which the development of 

 communications is of prime importance to the Government. The 

 countiy varies from barren desert in the north to tropical jungle in 



