Apri 18, 1912] 
om the sides of its valley, and often tends to 
engthen them, whereas ice slowly cuts away the toes 
f these spurs until they end in triangular facets. 
Phese facetted ends are well shown on many of the 
purs that run down to the Alpine glaciers, and they 
be recognised on many Scottish mountains and 
alleys. 
A Biksier flowing down a valley presses against the 
purs from the two sides and gradually rubs them 
way. It thus converts a sinuous river valley into a 
aight canal-like or trough-valley, which is the char- 
acteristic form of fiord valleys, of many glacier 
alleys, and of some of the lower Swiss valleys, such 
f the higher level Alpine valleys from which glaciers 
have retreated. 
There is also an important difference between the 
powers of ice and water in deepening their valleys. 
A river, except where it plunges over a waterfall, 
cannot deepen its valley lower than the outlet. Deep 
ock basins can only have been made by r-ver action 
by a combination of three processes: first, the eleva- 
tion of the country high above sea-level; secondly, the 
utting of deep valleys by rivers; and thirdly, the un- 
even subsidence of the land, so that the mouth of 
the valley either sank slightly or remained stationary, 
and was thus left as a raised threshold. The exist- 
ence of deep fiord basins and their thresholds cannot, 
however, be thus explained in many and in perhaps 
the majority of cases. 
Ice, however, has greater powers of irregular 
vertical excavation than water. It moves slowly, and 
its great weight presses heavily upon its bed. Frag- 
ments of the loose material beneath the ice may be 
frozen into the sole of the glacier and be thus carried 
away. There is much evidence that the power of a 
glacier to cut away fresh, undecayed rocks is limited, 
except where they project into the path of quickly 
moving ice; but ice acting on weathered, decomposed 
ock can pick it up and remove it grain by grain. 
Mining experience shows that the depths to which 
rocks are weathered varies very irregularly; along 
the outcrop of a lode there may be a succession of 
places where decomposition has gone deeply, separated 
by ridges of fresh and hard rock. A glacier has 
greater powers than a river in eating out such 
weathered material, and thus forming rock basins. 
The attack of glaciers on the rocks beneath them 
is aided by a second process. Many geologists hold 
that rivers owe their main power of cutting down 
hard bars of rock to pot-hole formation, which be- 
neath a river cannot extend deeply below sea-level; 
but there is no such limit to the depths to which pot- 
holes are bored beneath a glacier; a stream of water 
lunging down a glacier mill may drill pot-holes 
occur together the surface may be lowered into a 
rock basin. Hence glaciers have some powers of 
hollowing out basins greater than those of rivers. 
There are, however, other factors which counteract 
this process, and cause slowly moving glaciers and 
sheets of snow and ice to protect their beds, for the 
rock beneath them is preserved from the wear and 
frost, and from atmospheric decomposition. 
The distribution of fiords has also been claimed as 
proof of their glacial formation. There are nine 
main fiord districts in the world, and of these the 
most famous are in high latitudes and in districts 
which were formerly occupied by ice. Thus in Europe 
they occur in Norway, Scotland, Iceland, and Spitz- 
bergen. In America they are found in Greenland 
and down the western coast throughout Alaska and 
Canada. They disappear further south, and reappear 
again in the far south of South America in areas 
NO. 2216, VOL. 89] 
as that of the Rhone—though it is not the usual form | 
into hard rocks deep below sea-level, and where many | 
tear of wind and water, from shattering by heat and | 
NATURE 
| wall 
| recent Scottish Survey memoir. 
1d] 
where glaciers still exist upon the mountains, and 
there is clear evidence of the former extension of the 
glaciers to sea-level. 
The famous fiords of New Zealand are in the south- 
western corner of the country, where the glaciers 
formerly reached sea-level; while the North Island, 
where, according to many New Zealand geologists, 
there is no satisfactory evidence of low-level glaciers, 
has no fiords. 
It is therefore claimed that fiords are limited to 
countries that have been glaciated, and that their 
restriction to such regions is proof of their glacial 
origin. Nevertheless, in spite of its attractiveness, 
the simple theory which explains fiords as due to the 
action of glaciers appears inadequate. Many fiords 
| were no doubt occupied by ice, and have been moulded 
to their present form by ice; but they were not neces- 
sarily formed by it. Fiords are not limited to 
formerly glaciated areas, and even in glaciated 
countries their distribution is inconsistent with their 
glacial formation. Thus a sheet of ice covered nearly 
the whole of the British Isles, and, according to most 
authorities, it extended as far south as the line 
between the estuaries of the Thames and the Severn. 
The fiords of Great Britain are, however, almost 
limited to western Scotland, although the ice covered 
most of the eastern coasts, and there flowed over 
rocks of the same character as those beside the 
western fiords. Some of the glaciated areas in eastern 
England consist of soft beds, upon which glacial 
erosion should have been particularly effective. Never- 
theless, there are no fiords in Yorkshire, for example, 
although the hills that reach the coast. were buried 
under deep ice, and are composed of comparatively 
soft rocks. The best English fiords are in Cornwall, 
where some of the harbours, like those on the oppo- 
site coasts of Brittany, have many characters which 
show that they were originally true fiords; and Corn- 
is one of the few English counties which 
admittedly were not glaciated. 
Moreover, the plan of the fiord systems in each 
country does not appear to be that which would have 
developed as the result of glacial erosion. The chief 
fiord systems in the world have the same essential 
plan. Each fiord area is long and curved; in most 
cases a series of channels extend along the coast, 
and from them other fiords run inland, and are 
usually connected by others, or by deep valleys, so 
that the country is divided into angular blocks. 
These networks are not the arrangement that would 
be expected if fiords had been excavated by glaciers, 
for in that case the main channels should be radial 
from the chief centres of snow fall. The course of 
the fiords is inconsistent with the lines of flow of 
the chief glaciers. The glaciers discharged from the 
highlands or from great domes of snow which some- 
times formed on the lee side of the existing water- 
sheds; the ice flowed by the most direct channels to 
the nearest low land or the sea. Many of the fiords 
owing to their directions were quite useless to the 
| outflowing ice; they appear to have been simply filled 
with stagnant ice, and the main flow of the glaciers 
was above and across them. 
The inconsistency between the direction of the 
lochs and the lines of flow is well shown in many 
parts of Scotland, as. for example, by the map of the 
ice movements in the area around Colonsay in a 
Tt is also well shown 
main fiords, lochs, 
trend north and 
from east to west 
in the Shetland Islands, where the 
and other geographical elements 
south; but the ice movement was 
at right angles to the fiords. 
The final and most convincing argument against 
the glacial origin of fiords is that they are pre- 
glacial. They are older than the ice which once 
