
BANKS OF THE TWEED AND SOME OF ITS TRIBUTARIES. 551 
But the facts observable in Berwickshire, seem not to admit of this 
explanation. They suggest the supposition that a sea prevailed over this 
district, exceeding 1000 feet above the present sea-level, and probably much 
more. 
The facts alluded to are these— 
(1.) The extensive beds of sand and gravel, in many cases stratified, which 
abound in the district, not merely in the lower parts, but in higher parts also, 
up to the ranges of hills on each side of Tweed valley.* 
The relative position of these deposits favours that view; inasmuch as 
clay or mud occupies the lowest parts of the district, and gravel generally lies 
above the sand. 
(2.) The transport of boulders from the Highlands of Scotland across the 
estuary of the Forth, and also across two or three ranges of hills, necessitates 
the existence of a sea, with ice floating on it, to account for this transport. 
Even the boulders which have come merely across the Lammermuir and 
Cheviot hills, respectively require such an explanation. 
(3.) A new feature in this question is manifested by the form of the drift 
ridges, and their remarkable parallelism. 
My attention to it was first drawn by Sir Henry James, the Director of 
the Ordnance Survey, who, on seeing the shaded maps of the district made 
by his surveyors, sent to me a copy, accompanied by a note expressing his 
surprise at the immense number of “ lateral moraines ” existing in the valley of 
the Tweed. 
I am satisfied however, that these ridges are in no right sense moraines, 
seeing that they consist chiefly of stratified beds of sand and gravel. 
To one unaware of the composition of these ridges, and attending only 
to the circumstance of their longer axis being parallel with the ranges of 
hills forming the valley, the theory of lateral moraines was not unnatural. 
But when lateral moraines occur, they occur, as their name implies, only 
at the sides of valleys, and not over a great portion of the central parts of the 
valley, as is the case in our Border Counties. 
These ridges appear very similar to the submarine banks, composed of 
sand, gravel, or mud, in existing estuaries formed by the action of tidal 
currents. 
The sea charts, which give soundings and show the forms of submarine 
banks in estuaries, indicate many features similar to those which these kaims 
present. In the “ Estuary of the Forth” (page 99), there is a diagram indicat- 
* Mr Lustix, C.E., Edinburgh, tells me (18th May 1875), that in the parish of Temple (on the 
north side of the Lammermuirs) a bore was lately put down under his orders, which went through a 
solid bed of pure sand to the depth of 130 feet, without reaching rock. The spot is 800 feet above 
the sea, 
