Vol. 58.] TEESDALE, WEARDALE, AND THE TYNE VALLEY. 595 
of the Roman Wall, and is formed by the outcrop of the Great Whin 
Sill. The North Tyne cuts through this outcrop in the neigh- 
bourhood of Barrasford. 
The Great Whin Sill also crops out at the head of Alstondale, 
and at numerous points on the northern and eastern slopes of the 
Cross-Fell range. The Carboniferous Limestone and Yoredale Series 
cover most of the ground, but there are important outcrops of 
Millstone Grit capping the hills between Alstondale and West 
Allendale and Devil’s Water, and between the latter stream and the 
River Derwent. Several small faulted outliers of Coal-Measures 
occur in the valley of the South Tyne, between Haltwhistle and 
Hexham ; while for the last 20 miles of its course, the River Tyne 
flows over the rocks of the Northumberland coalfield. 
(2) The Glacial Deposits. 
The valley of the South Tyne above the town of Alston contains 
considerable quantities of bluish LBoulder-Clay, with scratched 
boulders consisting of the Carboniferous rocks of the Dale, together 
with a few boulders of Whin Sill. The Drift is of a similar nature 
in the tributary valleys, and also in the lower part of the main 
valley from Alston down to Lambley. 
_ The valley of the Nent, an important tributary which joins the 
South Tyne on its right bank at Alston, contains Boulder-Clay 
with local boulders, many of which are striated. 
Below Lambley the Drift assumes a reddish colour, and becomes 
more gravelly in texture. It is also much more widely distributed, 
being continuous with that of the Vale of Eden. In the neighbour- 
hood of Harperstown I found several pebbles of the granite 
of Eskdale in Cumberland ; also several boulders of Borrowdale 
andesite, together with large quantities of Carboniferous Lime- 
stone and shale and Whin-Sill dolerite. Between Featherstone 
Castle and Bellister Castle the Drift contains the full suite 
of rocks characteristic of the Drift beyond the Pennine water- 
shed round Carlisle and Brampton, together with Whin Sill. On 
the hill behind Bellister Castle (600 feet) the Drift contains a 
similar assortment of rocks. Seeing that this Drift is similar 
to that of the Brampton district in the Valley of the Irthing (of 
which I had made a hasty examination), I determined to visit that 
locality again, in order to investigate the matter more fully. 
The country between How Milland Brampton Junction is covered 
with Glacial gravels arrangedin mounds. Near Brampton Junction 
(400 feet) the gravel is reddish in colour, and contains pebbles of 
Borrowdale volcanics and large quantities of Triassic or Permian 
sandstone. Between Brampton Junction and Talkin’ Tarn is a 
large hollow lying between the gravel-hills, and containing a con- 
siderable quantity of peat, 4 feet of this deposit being exposed in a 
cutting. ‘This points to the presence of beds of clay below the 
gravel. Talkin’ Tarn lies in a similar hollow, and apparently has a 
