ON THE ORIGIN OF 
THE UPPER DRIFT SANDS AND GRAVELS 
OF NORTHUMBERLAND. 
G. W. BULMAN, M.A., B.Sc., 
Corbridge-on- Tyne. 
Wuart ate known as the ‘Upper Drift Sands and Gravels’ of 
Northumberland are a somewhat difficult series of deposits to 
decipher. They are found resting on the Boulder Clay, and fringing 
the sides of the chief valleys; and consist of very irregularly strati- 
fied sand and gravel of various degrees of coarseness. Their general 
appearance in section is strongly suggestive of river-action; the 
stratification is extremely rude and variable; the coarsest gravel may 
give place in a few feet or inches, both horizontally and vertically, 
to fine sand. Outwardly, they present characteristic rounded outlines, 
often hillocky and irregular, and add an important feature to the 
scenery of south-eastern Northumberland. 
Good sections are to be seen at Farnley and Thornborough Scars, 
a little to the east of Corbridge Station ; on the right bank of the South 
Tyne between Haydon Bridge and Bardon Mill; on the Wansbeck 
above Morpeth ; and on the Font, a tributary of the latter river. 
That they are aqueous and not glacial deposits is indicated by 
the existence of stratification, and the rounded state of the con- 
tained fragments; while the nature of the bedding points to 
fluviatile rather than marine conditions. 
As a broad and general outline of the manner in which these 
deposits were formed, I propose the following hypothesis :—During 
the prevalence of the ice-sheet and glaciers, the eastern and lower 
part of the county had its valleys and ravines filled up to a certain » 
height with boulder-clay, so as to form a broad level area above the 
old depressions. To this work of the ice is due one of the striking 
features in the physical geography of Northumberland at the present 
day, viz., the hilly western district, and the great plain of the eastern. 
Also as a result of ice-action, moraines fringed the sides of the 
valleys, and stretched across the country in lines marking the 
melting of the ice. As the intense cold passed away, rains and 
rivers commenced their work, and this morainic matter was carried 
down, more or less rounded, and spread out over the plain of boulder- 
clay. At the same time, portions of the clay itself would be denuded, 
and its scratched and striated pebbles mingled with the other gravel. 
As the rivers then rushed down the higher valleys, which had not 
been filled up by boulder-clay, they would have sufficient power to 
Feb. 1891. : 
