134
BATHYMETRICAL SURYEY OF
LOCHS OF THE TWEED BASIN
THE large area drained by the river Tweed (see Index Map, Fig. 15)
is on the whole remarkably devoid of lochs. It is true there are a dozen
little lochs on the borders of Roxburghshire and Selkirkshire, drained by
the Teviot branch of the Tweed, but they are very small, and were not
sounded by the Lake Survey. The principal loch is the well.known
St. Mary.s Loch, with the adjacent Loch of the Lowes, in Selkirkshire, on
FIG. 15.—INDEX MAP OF THE TWEED BASIN.
the Yarrow branch of the Tweed, while a notable addition has recently
been made by the construction, for the supply of water to the city of
Edinburgh and surrounding district, of the Talla reservoir in Peebles.
shire, which lies about 6 miles west of St. Mary.s Loch, on the Talla
branch of the Tweed. Of the three lochs surveyed, St. Mary.s Loch is the
largest and the Loch of the Lowes the smallest, Talla reservoir being
intermediate in point of size :—St. Mary.s Loch slightly exceeds 3 miles in
length, Talla reservoir is nearly 2½ miles in length, while the Loch of the
Lowes is less than a mile in length; the superficial area of St. Mary.s