
BANKS OF THE TWEED AND SOME OF ITS TRIBUTARIES. 503 
Were the English Channel to be raised out of the sea, would it not present 
a series of kaims or eskars very similar to those occurring in the Border 
Counties ? 
The general depth of the English Channel in this part, is from 150 to 200 
feet. The height of the submarine banks of course varies, but sometimes 
reaches 60 feet above the general level of the adjoining sea bottom. 
How the banks are formed, is a question of no moment in this dis- 
cussion. The sediment moved by the currents may be heaped up into ridges; 
or the sediment forming the ocean bed may be scoured out, leaving ridges 
standing up. 
In now turning to the map of the district (Plate XX XVIII.), it will be 
noticed that the kaims or ridges situated near one another, are approximately 
parallel, and that they observe a general parallelism to the range of hills on 
each side of the Border Counties. 
With regard to the depth of sea which prevailed when these kaims were 
formed, one thing is clear, viz., that the beds of sand and gravel, existing 
in several places as high as 700 or 800 feet, imply a sea which stood greatly 
above that level. Mr Austin, after studying the features of the English 
Channel (“‘ Geol. Soc. Journ.” for 1849, vol. vi. p. 83), says that “the moving 
power of the sea at 60 fathoms is limited to fine sand.” A somewhat 
similar opinion had been previously expressed by Lord Anson, as the-result of his 
nautical experience, when he says, that he generally found at the sea bottom, 
fine sands, mud, and ooze, at from 80 to 60 fathoms; sand with broken shells, 
at from 60 to 40 fathoms ; coarse sands, pebbles, and small stones, at from 
40 to 12 fathoms. 
According to these rules, if large accumulations of sand and fine gravel 
exist in Berwickshire and Roxburghshire up to a height of 700 or 800 
feet, the depth of the sea in which these beds were deposited, must have been 
at least 400 feet more, z.¢., from 1100 to 1200 feet. But we know that there 
aie parts of Scotland, in which thick beds of sand occur, at heights exceeding 
1500 feet above the present sea-level. 
The contour lines of the Border Counties show that when sea prevailed 
over them, a depression of the sea bottom existed along what is now the valley 
of the Tweed, and that the highest part of this depression was at St Mary’s 
Loch and Moss Paul. The tides would of course be stronger towards the head 
of the valley, where the hills on each side were closer, and the depth of water 
less. Hence, it is that, judging by the shaded maps of the Ordnance Survey, 
the kaims appear to be of larger dimensions in the higher parts of the valley. 
The great probability is, that the whole of the central parts of the Tweed 
valley were at one time occupied with detrital matter, at least 300 feet in thick- 
ness, most of which was subsequently removed by currents of water. Hence we 
VOL. XXVII. PART IV. 7G 
