232 The Great Ice Age and Origin of the “ Till.” [April, 
sea around Scotland would require to become deeper than now 
by 1400 or 1500 feet at least.” 
I axil unable to understand by what means Mr. Geikie 
measured this depth of the ice which covered these low 
grounds, except by assuming that its surface was level with 
that of the upper ice marks of the hills beyond. The follow- 
ing passage on page 63 seems to indicate he really has 
measured it thus : — 
“ Now the scratches mav be traced from the islands and 
*/ 
the coast-line up to an elevation of at least 3500 feet ; so that 
ice must have covered the country to that height at least. 
In the Highlands the tide of ice streamed out from the cen- 
tral elevations down all the main straths and glens ; and by 
measuring the height attained by the smoothed and rounded 
rocks we are enabled to estimate roughly the probable 
thickness of the old ice-sheet. But it can only be a rough 
estimate, for so long a time has elapsed since the ice dis- 
appeared, the rain and frost together have so split up and 
worn down the rocks of these highland mountains, that much 
of the smoothing and polishing has vanished. But although 
the finer marks of the ice chisel have thus frequently been 
obliterated, yet the broader effects remain conspicuous 
enough. From an extensive examination of these we gather 
that the ice could not have been less, and was probably 
more, than 3000 feet thick in its deepest parts.” 
Page 80 he says — “ Bearing in mind the vast thickness 
reached by the Scotch ice-sheet, it becomes very evident 
that the ice would flow along the bottom of the sea 
with as much ease as it poured across the land, and every 
island would be surmounted and crushed, and scored and 
polished just as readily as the hills of the mainland were.” 
Mr. Geikie describes the Scandinavian ice-sheet in similar 
terms, hut ascribes to it a still greater thickness. He says 
(page 404) — “ The whole country has been moulded and 
rubbed and polished by an immense sheet of ice, which could 
hardly have been less than 6000 or even 7000 feet thick,” and 
he maintains that this spread over the sea and coalesced with 
the ice-sheet of Scotland. 
My recollection of the Lofoden Islands, which from their 
position afford an excellent crucial test of this question, led 
me to believe that their configuration presented a direCt 
refutation of Mr. Geikie’s remarkable inference ; but a mere 
recollection of scenery being too vague, a second visit was 
especially desirable in reference to this point. The result 
of the special observations I made during this second visit 
fully confirmed the impression derived from memory. 
