GLACIATION OF SCOTLAND. 
175 
ter, and which must have been brought into their present po¬ 
sition since the time when the neighboring gulf was already: 
characterized by its peculiar fauna. Here, therefore, we have 
proof that the transport of erratics continued to take place, 
not merely when the sea was inhabited by the existing tes- 
tacea, but when the north of Europe had already assumed 
that remarkable feature of its physical geography which 
separates the Baltic from the Korth Sea, and causes the Gulf 
of Bothnia to have only one-fourth of the saltness belonging 
to the ocean. In Denmark, also, recent shells have been 
found in stratified beds, closely associated with the boulder 
clay. 
Glaciation of Scotland. —Mr. T. F. Jamieson, in 1858, ad¬ 
duced a great body of facts to prove that the Grampians 
once sent down glaciers from the central regions in all di¬ 
rections towards the sea. “ The glacial grooves,” he ob¬ 
served, “ radiate outward from the central heights towards 
all points of the compass, although they do not always strict¬ 
ly conform to the actual shape and contour of the minor val¬ 
leys and ridges.” 
These facts and other characteristics of the Scotch drift 
lead us to the inference that when the glacial cold first set 
in, Scotland stood higher above the sea than at present, and 
was covered for the most part with snow and ice, as Green¬ 
land is now. This sheet of land-ice sliding down to lower 
levels, ground down and polished the subjacent rocks, sweep¬ 
ing off nearly all superficial deposits of older date, and leav¬ 
ing only till and boulders in their place. To this continent¬ 
al state succeeded a period of depression and partial sub¬ 
mergence. The sea advanced over the lower lands, and Scot¬ 
land was converted into an archipelago, some marine sand 
with shells being spread over the bottom of the sea. On this 
sand a great mass of boulder clay usually quite devoid of 
fossils was accumulated. Lastly, the land re-emerged from 
the water, and, reaching a level somewhat above its present 
height, became connected with the continent of Europe, gla¬ 
ciers being formed once more in the higher regions, though 
the ice probably never regained its former extension.* Af¬ 
ter all these changes, there were some minor oscillations in 
the level of the land, on which, although they have had im¬ 
portant geographical consequences, separating Ireland from 
England, for example, and England from the Continent, we 
need not here enlarge. 
Mammoth in Scotch Till ,—Almost all remains of the ter¬ 
restrial fauna of the Continent which preceded the period of 
* Jamieson, Quart. Geol. Journ., 1860, vol. xvi., p. 370. 
