12'2 Notea oil Ike Ucvloyij of Curhrldfjc. By G. A. Lcbour. 



foreign to it— slaty, greywacke, and igneous rocks akin to those 

 of Cumberland and Southern Scotland. This distinction between 

 the Drift and Alluvial gravels is easily made in writing, but is 

 by no means so easily arrived at in the field, since mixed with 

 the true alluvium must necessarily and constantly be found 

 pebbles fallen from the topographically higher-lying and older 

 gravels. 



It has been the custom to call these hill-side gravels and sands 

 which fill up the valleys of the Tyne, Derwent, and Wear, some- 

 times as far as the 700 feet contour line, the "Middle Glacial 

 Sands and Gravels." They undoubtedly correspond to many 

 deposits which in other parts of England are usually so termed, 

 but nothing has been better proved by the recent wide-spread 

 investigations in British glacial geology than the fact that these 

 deposits are not strictly equivalent among themselves. No good 

 purpose can therefore be served by adopting a title which in the 

 present case would be especially misleading, since nowhere with- 

 in the district is there any Upper Boulder Clay. But although 

 all that can be said as to the position of these loose beds is that 

 they overlie the Boulder Clay or Lower Boulder Clajr, their 

 Glacial age is tolerably well ascertained, scratched and striated 

 stones having from time to time been found in them.^' In the 

 fine bluff which forms the back-ground to the "Rifle Volunteers' 

 targets west of the Corbridge Station the sands and gravels can 

 be well studied. There the current-bedding of the sands with 

 patches of coal-debris presenting wedge-ended lenticular sections, 

 and the unconformable junction with the Boulder Clay beneath, 

 are exposed in a steep river cliff of which the face is continually 

 changing, owing to constantly recurring falls. The coarser 

 gravelly faces of the deposits is m^et with also on the hills over 

 which the footpath from Corbridge to Aydon Castle runs. 



Boulder Clay : Of this no very remarkable sections need be 

 called attention to. It is present over a considerable portion of 

 the entire tract under notice, wherever the solid rock does not 

 come to the surface, from the high ground about and north of 

 the Eoman Wall. The valleys occupied by the Erring Burn and 



* The above statements must be taken in a broad sense. There are often 

 adventitious beds of sand and gravel in the Lower Boulder Clay, and also 

 beds of clay (probably re-assorted Boulder Clay, but without scratched 

 Boulders) in the Drift between Wansbeck and Wear. These, however, 

 are in nowise continuous, and cannot for a moment be compared either 

 with the sands and gravels under consideration, nor with the so-called 

 Middle Glacial Beds of other areas. 



