June 2, 1904] 



NA TURE 



EMERGENCE AND SUBMERGENCE OF LAND. 

 A T the recent anniversary of the Geological Society, when 

 -^ the president was unable from illness to be present, 

 his place was taken by Sir Archibald GeiUie, who prepared 

 an address for the occasion on the evidence supplied by the 

 British Isles as to the problem of the causes of changes in 

 the relative levels of sea and land. This address appears 

 in full in the Quarterly Journal of the society, and we here 

 reproduce it in abstract. 



(i.) Emergence. — Geologists in the British Isles have long 

 indulged the confident belief that Raised Beaches afford 

 •demonstrative proof of changes in the relative levels of sea 

 and land. The abundant and striking examples of them 

 -around our coasts have been universally accepted among 

 us as marking former sea-margins, whether the sea be 

 supposed to have risen upon the land or the land to have 

 been upheaved above the sea. The recurrence of precisely 

 similar terraces along the western coast of Norway, but on 

 a still more impressive scale, has been regarded as furnish- 

 ing evidence of an extensive emergence of land, from the 

 south of Britain to the northern end of the Scandinavian 

 peninsula. Prof. Suess, however, seeks to show that, at 

 least as regards the north-western coast of Norway, these 

 opinions are based upon a misreading of the evidence. After 

 his visit to that region, and his study of the literature of 

 the strand-lines, there so wonderfully developed, he has come 

 to the conclusion that the Norwegian fjords furnish no 

 argument against his doctrine that there has been no recent 

 upheaval of the land. He asserts that " we must interpret 

 all the scler [rock-shelves] and the great majority of the 

 terraces in the fjords of Western Norway as proofs of the 

 retreat of the ice that once covered so much of the peninsula, 

 and not as proofs of any oscillations of the surface of the 

 ■sea, still less of any movement of the solid land." It 

 would widen the inquiry too much to enter upon an ex- 

 .-imination of the evidence as it is presented in Scandinavia. 

 But the author of the address, having been all his life 

 familiar with the strand-lines of this country, and having 

 traced those of the Norwegian coast from Bergen to 

 Hammerfest, directed attention to one or two of the insuper- 

 able difficulties with which Prof. Suess 's theoretical explan- 

 ,-ition seemed to him to be beset. The great .Austrian 

 geologist appears to have unwittingly confounded two sets 

 ■of beach-lines, which differ a good deal from each other in 

 general character, and are entirely distinct in origin. Avail- 

 ing himself of the remarkably full and interesting researches 

 •of Scandinavian geologists regarding the glaciation of their 

 country, he dwells upon the importance of the terraces left 

 by the fresh-water lakes that were dammed back by the 

 great ice-sheet as it retired. He believes that these pheno- 

 mena extended even to the Norwegian coast, and that the 

 strand-lines of the fjords, whether in the form of platforms 

 eroded out of the solid rock (seter) or terraces of sediment, 

 mark former levels of lakes that filled these valleys when 

 their mouths were blocked up with the ice-sheet. .'Vs the 

 lowest of these strand-lines includes sands and gravels 

 crowded with marine shells, he is compelled to admit that 

 it marks a former sea-beach. But he endeavours to dis- 

 criminate between it and the other horizontal shelves, which 

 follow it in parallel lines at higher levels. He affirms that 

 the latter present a series of " characters absolutely irrecon- 

 cilable with what we know of the action of the sea along 

 a shore " — such as the series of fragmentary terraces found 

 at increasing heights inland, their absence from the parts 

 near the general coast-line, and the breadth of the seter. 

 He passes lightly over the fact that some of these higher 

 tei races have yielded marine organisms which are pro- 

 gressively of more .'\rctic character, according to their alti- 

 tude, and according, consequently, to the antiquity of the 

 -■fdiments in which they lie. 



Now, according to the experience of those northern 

 geologists who have specially studied Scandinavian glaci- 

 ation, the lakes that were formed by the ponding-back of 

 the drainage against the flanks of the ice-sheet lie to the 

 east of the watershed of the peninsula. These observers 

 have ascertained that when this ice-sheet was waning, it 

 retreated eastward from the backbone of the country and 

 ■n on the eastern or Swedish slope, leaving a gradually 



NO. 1805, VOL. 70] 



increasing breadth of ground clear of ice. The streams 

 flowing eastward over this liberated area had their drainage 

 arrested against the margin of the ice; and hence arose a 

 vast series of lakes which lasted for longer or shorter 

 periods, until, by the continued creeping backward of the 

 ice, their contents were drained off to lower levels. A 

 multitude of records of old water-levels, or " strand-lines," 

 was thus left over the surface of the country. It is the 

 opinion of Scandinavian geologists that all the terraces not 

 of marine origin lie within that area. 



As one of the distinctive characters of the shore-lines left 

 by the glacier-lakes, the author of the " Antlitz der Erde " 

 cites the occurrence of the rock-shelves or platforms (seter) 

 eroded out of the solid rock, and he refers the origin of 

 these common features of the fjords to the daily oscillations 

 of temperature at the surface of the lakes. A reference 

 to the abundant examples of such rock-shelves in our own 

 islands showed that this explanation is at least in- 

 adequate. If, however, for a moment, we grant 

 that the strand-lines, including the seter of the Norwegian 

 fjords, do mark levels of former fresh-water lakes, 

 it is obvious that, in order to pond the drainage back 

 and produce these lakes, the mouths of the fjords must have 

 been in some way blocked up by a barrier which has dis- 

 appeared. If this barrier were land-ice, as Prof. Suess 

 appears to assume, the water would rise behind it, until, if 

 the overflow found no escape into the Atlantic, it would pass 

 over the watershed, and joining the various bodies of water 

 that were there intercepted by the great Swedish ice-sheet, 

 would eventually find its way into the Gulf of Bothnia. 

 There would thus be two huge bodies of ice, between which 

 the drainage was accumulated. We must remember, how- 

 ever, that the strand-lines are not confined to the fjords, but 

 sweep round the coast on either side, and even appear on 

 the islands that flank the mainland of Norway, some of 

 them actually looking out to the open sea. The supposed 

 ice-sheet must therefore have lain mainly outside these 

 islands. But there is absolutely no evidence of any such 

 detached western ice-body, and every reason to believe that 

 it never existed. 



.At the period of maximum glaciation the ice-sheet prob- 

 ably advanced westward beyond the present limits of the 

 land. But, when it began to retreat, it would naturally 

 creep backward up the fjords, which would be still the main 

 lines of ice-drainage. We can conceive, indeed, that at an 

 early stage of this retreat, a glacier or ice-lobe may here 

 and there have blocked up a large valley and produced a 

 lake, as in the instances cited by Prof. Suess from Green- 

 land. But the strand-lines of western Norway are not ex- 

 ceptional phenomena. They continue as characteristic 

 features of the coast-line and of the fjords for several hundred 

 miles, and must owe their origin to some general and widely 

 extending cause. That they are true sea-beaches, as has 

 been generally believed, Sir .Archibald Geikie had not the 

 smallest doubt. 



Fortunately, we possess in our own islands a body of 

 evidence bearing on this question, not certainly as 

 voluminous and impressive as that of Scandinavia, but 

 having the compensating advantage of great simplicity and 

 clearness. On the one hand, the famous Parallel Roads of 

 Glen Spean and Glen Roy, and those of other less known 

 valleys, stand out as acknowledged relics of glacier-lakes : 

 while round our coasts, on both sides of the country, raised 

 beaches, which have been hitherto regarded as old sea- 

 margins, run for hundreds of miles. These two series of 

 terraces are found close together, yet there is no difficulty 

 in drawing a satisfactory distinction between them. Indeed, 

 their proximity enables us all the more clearly to perceive 

 their contrasts. 



There must, of course, be certain general resemblances 

 between the littoral formations of lakes and of the sea. 

 The erosion produced by the waves or wavelets of a body 

 of fresh water is similar in kind to that performed by the 

 sea, although different in degree. In like manner, the 

 beaches of deposit formed in lakes possess, on a minor scale, 

 many of the characters of those accumulated along the sea- 

 shore. And it may readily be granted that, in isolated 

 e.xposures of some old beach, it may be difficult or impossible 

 to decide, in default of evidence from elsewhere, whether 

 the phenomena observable are to be assigned to the work 



