554 D. MILNE HOME ON HIGH-WATER MARKS ON THE 
find in some places, kaims near the river, parallel with its course, which are 
merely portions of a pre-existing sea bottom, the detritus on each side having 
been scoured out and removed. To this class may belong the very interest- 
ing kaim at Wark, on the north side of which the Tweed now runs. That the 
Tweed had previously run on the south side of this kaim, is pla from the 
configuration of the ground. So also at Norham, there is a kaim, on which 
the church stands. There is a hollow along the south side, through which the 
river ran, before it passed into the lower channel on the north side. 
6. If the theory of a sea prevailing at a height of 1000 feet or more, be 
adopted, it enables us to account for many other facts. 
I do not discuss the question how the relative levels of sea and land 
altered, till they reached the present condition of things; whether it was by 
the land rising or by the sea falling. Whichever way it was, the change 
seems not to have been accomplished at once. There have been successive 
periods at which those ancient sea margins were produced. 
I admit that those sea margins, particularly at levels above 100 feet, are, 
in this part of Scotland, famt and seldom continuous. But if beach lines at 
low levels are well marked, and now acknowledged by experienced and cautious 
geological observers to be beach lines, their existence lends probability to others 
having in like manner been produced at higher levels. Let us see, then, what 
reliable evidence there is of comparatively low sea margins. 
A sea margin 9 to 12 feet above the present high water mark, on both sides 
of the English Channel, is avouched by Mr Gopwin Austin, and on the south 
coast of Ireland by Mr Kinanan of the Irish Survey. 
A horizontal line at that height has been long recognised on many parts of 
the coasts of Scotland (“‘ Estuary of the Forth,” p. 105). 
Messrs Brapy, CrosskEY, and RosBERTSoN, ina recent paper in the Transac- 
tions of the Paleontological Society, avouch two lines on the Scotch coasts, 
one at 25 feet, the other at 40 feet. Mr Kinanan refers to one on the Irish 
coast at 35 feet. 
Mr PenceEty (“ Lond. Phil. Trans.” for 1873, p. 182), refers to a raised 
beach all along the south coast of England, at a height of 30 feet, containing 
sea shells of the existing species.* 
' Sir Henry pe 1A Becue (“Geology of Cornwall,” p. 425), describes a 
raised sea beach on the coast of Cornwall, at a height of 50 feet above the pre- — 4 
sent sea-level. 4 
* The slight discrepancy as to the height of these old sea margins, as given by different authors, 
may arise from the measurements being made, in some cases, from high-water mark ; in others, from 
the supposed medium sea-level. All the Ordnance Survey measurements are from the medium sea- 
level. But as it is almost impossible for geologists, in their excursions, to ascertain the medium sea- 
level, they invariably measure from ene apparent line of the last high water, produced by a spring ora 
neap tide. a 

