66 Dr. D. Woolacott—The Interglacial Problem. 
be regarded as a raised beach, but Smythe considers it to be similar 
in origin to that at Horsebridge Head ; pointing to a passage of ice 
from the north after the deposition of the western derived Drift. 
Is it possible that the Lyne Burn deposit is also an Interval- or 
Interglacial deposit ? The critical examination of such beds makes 
the Drift of the north-east of England much more complicated than 
it at first appears to be. 
2. In the papers on the Superficial Deposits and the Origin and 
Influence of the chief physical features of Northumberland and 
Durham, certain regularly-bedded shell-bearing gravels and sands 
occurring up to the 150-feet contour were described as raised 
beaches. Various arguments have been advanced by different 
geologists against considering these deposits as uplifted marginal 
sea-deposits, such as, they cannot be traced north of Tynemouth nor 
along the Yorkshire coast nor far inland, also that shell-bearing 
sands and gravels that have been carried inland by ice occur in 
Durham at a higher level; but all such arguments disappear before 
positive evidence obtained from an examination of the deposits. 
In the June number of the GroLtocicaL MaGazineE for 1920 there is 
described an exposure of these beds at Hasington, from an examina- 
tion of which it should be possible to definitely decide whether these 
deposits are raised beaches.1 After the exact method of the formation 
of these sands and gravels has been agreed upon, their extent and 
peculiarities may be more fully discussed. 
The submerged forests of the Durham coast rest on boulder-clay ; 
that at Whitburn Bay is certainly formed from a growth of vegeta- 
tion in situ. They appear to mark a slight recent depression, but 
there is the distinct possibility that their present relation to the sea- 
level is due among other causes to the slipping and settling down of 
the superficial deposits in the valleys and depressions in which 
these formations rest, and therefore that they do not mark any 
regional sinking of the crest. 
The complex character of part of the Superficial Deposits in the 
north-east of England can be studied in the Tyne valley. These 
have been carefully examined by HE. Merrick, who has worked out the 
sequence of the beds.2,_ The Preglacial ‘‘ Tyne” reaches a maximum 
depth beneath sea-level of 169 feet at Dunston, west of Gateshead, 
about 10 miles inland, while at its mouth it is only 141 feet. The 
slope of bed rock is of a switchback nature due to the formation of 
a series of rock basins along its course by glacial action. This old 
depression is partly filled by a series of deposits of very varying 
character, the exact origin of which is very difficult in some cases to 
determine. They probably include true glacial deposits of boulder- 
clay, fluvio-glacial beds, glacier-lake deposits, estuarine deposits 
(formed when the coastal region was embayed at the time of the 
1 | regard them as true Raised Beaches. 
2 “On the Superficial Deposits around Newcastle-upon-Tyne’’: Proc. 
Univ. Durham Phil. Soc., vol. iii, pt. iii, 1909. 
