^'ov. 25, 1 886] 



NATURE 



91 



There is abundant evidence to prove that the ice-lobe filling 

 the Irish Sea was thicker towards its axis than at its edges, and 

 at the north than at its southern terminus, and that it was re- 

 inforced by smaller tributary ice-stream5 from both England and 

 Ireland. It may be compared with the glacier of the Hudson 

 River Valley in New York, each having a maximum thickness 

 of something more than 3000 feet. The erosive pDwer of the 

 ice-sheet was found to be extremely slight at its edge, but more 

 jiowerfnl farther north, where its action was continued for a 

 longer period. Towards its edge its function was to fill up in- 

 equalities rather than to level them down. It was held that 

 most glacial lakes are due to an irregular dumping of drift, 

 rather than to any scooping action, observations in England 

 and in Switzerland coinciding with those in America to confirm 

 this conclusion. Numerous facts on both sides of the Atlantic 

 indicate that the upper portion of the ice-sheet may move in a 

 different direction from its lower portion. It was also shown 

 that a glacier in its advance had the power of raising stones 

 from the bottom to the top of the ice, a fact due to retardation 

 by friction of its lower layers. The author had observed the 

 gradual upward passage of sand and stones in the Grindelwald 

 glacier, and applied the same explanation to the broken shells 

 and flints raised from the bed of the Irish Sea to the top of 

 Moel Tryfan, to Macclesfield, and to the Dublin mountains. 



The occurrence of stratified deposits connected with un- 

 doubted moraines, was shown to be a common phenomenon, 

 and instances of stratified moraines in Switzerl.and, Italy, Ame- 

 rica, and Wales, were given. The stratification is due to waters 

 derived from the melting ice, and is not proof of submergence. 



It was held that, notwithstanding a general opinion to the 

 contrary, there is no evidence in Great Britain of any marine 

 submergence greater than about 450 feet. It was to be ex- 

 pected that an ice-sheet advancing across a sea-bottom should 

 deposit shell-fragments in its terminal moraine. The broad 

 principle was enunciated that wherever in Great Britain 

 marine shells occur in glacial deposits at high levels, it can be 

 proved both by stria: and the transport ot erratics that the ice 

 advanced on to the land from out of the sea. The shells on 

 Three Rock Mountain near Dublin, and in North Wales and 

 Macclesfield, all from the Irish Sea ; the shells in Cumberland 

 transported from Solway Firth ; those on the coast of North- 

 umberland brought out of the North Sea ; those at Airdrie in 

 Scotland, carried eastward from the bottom of the Clyde ; and 

 those in Caithness from Moray Firth, were among examples 

 adduced in proof of this principle. The improbability of a 

 great submergence not leaving corresponding deposits in other 

 parts of England was dwell upon. 



It was also held that there was insufficient evidence of more 

 than one advance in the ice-sheet, although halts occurred in its 

 retreat. The idea of successive elevations and submergences 

 with advances and retreats of the ice was disputed, and the 

 author held that much of the supposed inter-glacial drift was due 

 to sub-glacial waters from the melting ice. 



The last portion of the paper discussed the distribution of 

 boulders, gravels, and clays south of the glacial area. Much the 

 greater part of England wa; believed to have been uncovered by 

 land ice. The drift deposits in this area were shown to be the 

 result in part of great fresh-water streams issuing from the melting 

 ice-sheet and in part of marine currents bearing icebergs during 

 a submergence of some 450 feet. The supposed glacial drift 

 about Birmingham and the concentration of boulders at Wolver- 

 hampton were regarded as due to the former agent, while the 

 deposits at Cromer and the distribution of Lincolnshire chalk 

 across Southern England were due to the latter. The supposed 

 esker at Hunstanton was held to be simply a sea-beach, and the 

 London drift deposits to be of aqueous origin. Thus the rival 

 theories of floating icebergs and of land glaciers were both true, 

 the one for Middle and Southern England, the other for Scot- 

 land, Wales, and the North of England ; and the line of de- 

 markation was fixed by great terminal moraines. The paper 

 closed with an acknowledgment of indebtedness to the many 

 geologists in England and Ireland who had uniformly rendered 

 generous assistance during the above investigation. 



THE CLIMA TE OF NORTHERN EUROPE AND 



THE GULF STREAM 

 T N view of the reference made by Sir ^\'ilIiam Dawson, in his 

 inaugural address at the meeting of the British Association, 

 to the effect of the Gulf Stream on the climate of Northern 



Europe, particularly that of Norway, and the consequences of 

 a diversion of the stream from its present course, the following 

 contribution to the subject by the well-known Norwegian 

 savaW, Dr. Karl Hesselberg, which appeared in a recent 

 number of the scientific journal Naturen, may be of interest and 

 tend to its further elucidation. 



According to the situation of Norway on the globe, the 

 northern part of the country should have a distinct Polar 

 climate, with eternal ice and snow, a home only for the Eskimo 

 and Polar bears. Several circumstances contribute, however, to 

 make it otherwise. The country forms a western promontory of 

 the great Asiatic-European continent, and receives its full share 

 of the advantages of such a situation. Mild south-west winds 

 blow throughout the year, while warm sea-currents wash its 

 extensive shores summer as well as winter. The winter cold is 

 so reduced that only a small portion of the heat of the summer 

 sun is consumed in melting the snow. The length of the summer 

 days, too, which north of the Polar Circle last twenty-four hours, 

 contribute to raise the mean temperature, and accelerate the 

 growth of the flora. Certain other circumstances, as, for in- 

 stance, the formation of the country and the physico-geographical 

 conditions of the North Atlantic Ocean, contribute equally to 

 make the Norwegian climate one of the most favourable iu the 

 world. A brief /vj/rwt-' of the circumstances will be of interest. 

 A chart of the distribution of the atmospheric depression in 

 the North Atlantic Ocean — the Norwegian Sea — shows that all 

 the year round a strong barometric minimum prevails in the 

 middle of the sea between Norsvay, Iceland, Jan Mayen, and 

 Spitzbergen, the consequence of which is that south-west winds 

 always blow in the eastern part of this area, viz. along the coast 

 of Norway. Warm water is thereby forced up towards Norway 

 and Spitzbergen, even into the East Arctic Ocean. The bottom 

 formation of the sea, too, contributes to ('reserve the high 

 temperature. If a chart be examined of the depths of the 

 North Atlantic Ocean, such a one, for instance, as is the result 

 of Prof. Mohn's labours after the measurements of the Norwegian 

 North Atlantic Expedition, it will be found that the sea-bottom 

 between Norway, the Faroe Islands, Iceland, and Jan Mayen, 

 forms a basin with a depth of a little over 2000 English fathoms. 

 It will also be seen that the Norwegian coast does not fill 

 abrup'.ly into this abyss, but that the bottom along the whole 

 coast slopes gradually down from the shore seawards to a certain 

 point where it terminates perpendicularly. In other words, 

 Norway is surrounded with a continuous "bank," which in a 

 great measure contributes to preserve the high temperature along 

 the coast, In the great basin, however, the water is icy cold at 

 the bottom, but against this the bank forms a natural barrier, 

 whilst above the bank the warm water is without any bottom 

 layer of cold. It is the warm water which fills the fjords 

 and there preserves a temperature so high that it is some- 

 times higher than the mean temperature of the air, and 

 under which the fjords do not freeze, a circumstance of 

 great importance. If the temperature of the sea-water in 

 the winter contributes to raise the temperature of the 

 air, it will in the summer have the opposite effect, and 

 cause the climate to be very much tempered along the coast. 

 It is only in the fjords and adjacent valleys that the temperature 

 in the summer rises to a height unusual for the latitude. 



In order to show the relatively favourable climate which 

 Norway enjoys, Dr. Hesselberg supplies two diagrams. The 

 first of these shows the mean temperature of the air over 

 Europe and the North Atlantic Ocean in January, when it 

 is lowest. Isotherms are shown for every fifih degree. If 

 now, for instance, the isotherm o°— the temperature of the air 

 —be followed, it will at once be seen how far it shoots up 

 northwards between Iceland and Norway, in fact, right above 

 lat. 70° N. In tead of running east and west, it goes nearly 

 straight north and south, particularly along the west coast of 

 Norway, which it follows throughout its entire length, from the 

 latitude of Tromso to that of Christiansand. Hence it deviates 

 towards Denmark, then runs into the Baltic, returns to Ham- 

 burg, and thence runs in a south-easterly direction across 

 Europe, nearly down to the Adriatic Sea. Here it first trends 

 eastwards, across Turkey and the Black Sea. Off the Nor- 

 wegian coast, therefore, in lat. 70° N., the same mean teinpera- 

 ture prevails in January as in Southern Europe in lat. 45°, and 

 even there the "mean temperature is probably 3° higher than 

 might be expected according to the latitude. The other 

 isotherms have a similar course, as well as the temperature at 

 the surface of the sea. A great wave of warm water rolls up 



