Vol. 60.] THE VALLEY OE THE TEIGN. 325 



Haidon area. "We know, too, that the Bovey Beds extend as far as 

 Pullabrook, about a mile south of Lustleigh, and are there about 

 440 feet above the sea. In Eocene time, this place may have been 

 some 500 feet above the level of the Haidon area ; and this will 

 account for the rapid increase in the thickness of the Bovey deposits 

 to the eastward, and for the great thickness that they attain at 

 Heathfield, where a boring traversed 520 feet without reaching 

 their base. 



I think, therefore, that we may imagine the surface-conditions of 

 the Upper Eocene Epoch in Devonshire to have been as follows : — 

 An extensive lake or lagoon, very little above the surface of the 

 neighbouring sea. extending over the whole of Eastern Devonshire 

 and across the central parts of the county north of Dartmoor; then 

 steep slopes formed of Palaeozoic rocks, up to a hill-region composed 

 partly of such rocks and partly of the Dartmoor Granite. The sub- 

 sidence of Upper Eocene time seems to have carried the lacustrine 

 area some 600 feet or so below the level at which it stood to besrin 

 with ; but probably deposition kept pace with depression, so that 

 the water was always shallow. By this subsidence the flanks of 

 Dartmoor were partly submerged, but the area of highland was 

 hardly diminished. 



Eocene time closed with a general upheaval of the whole British 

 area, the greater part of England becoming dry land, and the 

 water-space being contracted to a comparatively-narrow sea lying 

 over parts of Hampshire, Dorsetshire, and the English Channel. This 

 upheaval would leave the greater part of Devonshire covered with 

 a mass of Eocene beds banked up against the highlands of Dartmoor 

 and Exmoor. 



As the only Oligocene sea that we know of lay to the east of Devon- 

 shire, it is reasonable to suppose that the prevalent slope of the 

 western land was easterly. It is possible, indeed, that the 

 uplift of Oligocene time was somewhat unequal, being greater 

 in the west than in the east, so that a general easterly tilt was thus 

 early given to the Eocene beds all over England. We cannot yet 

 say positively when the Bovey Basin began to be formed ; but I 

 know of no special reason for connecting it with the early Oligocene 

 upheaval, and it seems much more likely to date from a later epoch. 



I conclude, therefore, that we may safely assume that when the 

 country arose from the Eocene sea, the streams running eastward 

 off the watershed of Dartmoor begnn to excavate channels through 

 the Eocene deposits which flanked that area; and that these streams 

 were tributaries of a great river which flowed eastward into the 

 Oligocene sea, over a tract of land which has long since vanished 

 and has become part of the English Channel. It follows that the 

 streams which now run from north to south were then insignificant, 

 and were only represented by short tributaries of the eastward- 

 flowing rivers. 



The courses of the rivers of Southern England seem to indicate 

 the influence of two slopes, one prevailing at one time and one at 



