562 Proceedings of the Royal Society 
A particular account was given of various localities where flat 
land or terraces in Tweed valley, at various heights above the sea, 
were recognisable. When the flat of 115 to 120 feet existed, the 
sea reached to Kelso ; and there, at that time, the Tweed would 
join the sea. As the sea fell — say 30 or 40 feet, to Coldstream — - 
the River Tweed would cut out a deeper channel for itself, and 
when the sea fell so much more, its channel would he still more 
deepened, till it reached the present sea-level. During these 
periods, when the river ran in one channel after another, flood- 
marks would be made on its banks, traces of which would long 
remain, though it is only the most recent which can be expected 
to be now visible. 
IV. — Views of other Persons. 
1. As to the drift deposits — 
(1.) Several geologists have ascribed the formation of the parallel 
ridges of drift deposits in Tweed Valley to the action of land-ice, 
and suppose that some of these ridges are lateral , others terminal 
moraines. 
(2.) They have also been ascribed to fluviatile action, aiding 
that theory by the supposition that enormous floods were in former 
times caused by the climate being more rainy, or by the melting 
of ice and snow on the hills. 
The author combated both views, holding that as similar ridges 
of sand, gravel, and mud are formed now in the sea, so they may 
have been formed in this district, when the district was under the 
sea. 
2. As to the high flood-marks on the river, reference was made 
to the opinions of Mr Alfred Tylor, and of the Rev. Thomas Brown, 
of this society, as to the probability that those marks were made 
by the rivers flowing in their existing channels. 
The author combated this theory, stating, that when the sea stood 
at higher levels all the rivers of the country must have likewise 
flowed in channels at higher levels, and that the flood-marks in ' 
question were formed then. 
