290 Geological Society :— 
The author considers these points, and concludes that in 
Oligocene time a thick mantle of soft Neozoic strata must have 
stretched across Devon and the adjacent parts of the English 
Channel; that this mantle consisted mainly of Selbornian Sands 
and of the later Eocene deposits, the latter overlapping the 
former and passing onto the surface of the Paleozoic rocks ; 
further, that these Eocene deposits covered all the central parts 
of Devon, and were banked up against the northern, eastern, and 
southern sides of Dartmoor. He assumes, moreover, that the post- 
Eocene elevation of the region gave this surface a general easterly 
slope ; and consequently that, although streams ran off Dartmoor in 
all directions, those which drained eastward had the longer courses 
and passed from the moorland area onto a plain, the drainage of 
which was directed eastward to the shore of the Oligocene sea. 
The general direction of the Upper Teign where it flows over the 
granitic area is east-north-easterly ; the direction of its gorge as far 
as Clifford Bridge is nearly due east, and if the conditions were 
as above described, the precursor of this river is not likely to have 
followed the course of the present river beyond Clifford Bridge. 
There is not likely to have been any ridge or obstacle that would 
have deflected it so far to the southward, nor anything to prevent it 
from continuing its easterly course towards, and probably across, the 
valley of the Exe. 
The valley of the Lower Teign below Dunsford is not likely to 
have existed in Oligocene time, but was part of the eastward 
sloping plain; the local drainage, however, may have been carried 
by a little brook flowing southward or south-eastward to join the 
river which was then initiating the valley of the Teign estuary. 
The erosion of the present longitudinal valley out of the Paleozoic 
rocks must have been accomplished in much later times, and was 
probably due to the development of the Permian escarpment. 
The valley through which the Teign now flows from Newton to 
Teignmouth traverses this escarpment; and its excavation can only 
be attributed to a stream that flowed eastward from higher ground 
than the summit of Little Haldon. Such a stream is the Lemon or 
Leman, which rises on the east side of Dartmoor at a level of 
about 1200 feet above the sea. The ancestor of this stream must 
have carved its channel out of the ancient plain of Eocene deposits ; 
and it is suggested that the valley of the Teign estuary is a portion 
of this ancient valley, which has survived all subsequent changes, 
except that of being cut down to modern base-levels. 
The change which led to the diversion of the Upper Teign into 
this more southern valley is attributed to the later earth-movements, 
which gave a southerly tilt to the whole region, and a still greater 
local tilt owing to the formation of the Bovey syncline. This tilt 
would increase the velocity and erosive power of the stream which 
was then carving out the valley west of the Haldon Hills, and as 
it gradually cut down to a lower base-level, the little affluents 
which formed its head-waters would cut back northward into the 
