June 26, 1884J 



NA TURE 



20' 



ings which are shown — certainly not very marked— seeni to point 

 in this direction, while the smoothing along the lower levels of the 

 holms referred to above are generally met with more in the 

 parts most exposed to the fury of the sea than inland. The 

 smoothing appears but rarely in spots on the lee side of the 

 ocean, even where they might be assumed to have been very 

 exposed to the glaciers. I have therefore come to the conclusion 

 that the smoothing phenomena observed here must be ascribed to 

 the erosion of the sea, which, under its action in the littoral belt, 

 carries with it finer as well as coarser materiils of scouring. 

 Stria? have nowhere been observed on the Ris Island or the sur- 

 rounding idands. 



If ice-streams from the southern part of the Scandinavian 

 peninsula have carried blocks from the mountain plateaux of 

 Sweden and Norway across the Central European plain to 

 England, to the Orkneys, and the Shetlands, an ice-stream 

 moving along the Balsfjord and further along the channel 

 described above through the Kval Sound should naturally have 

 progressed in the same manner, and strewn blocks along its 

 whole course. This is, however, not the case. On the Ris 

 Island, thus, and surrounding islands, not a single boulder or 

 travelled block whose place of birth could have been on the up- 

 land behind has been found. The mountains along the Bals- 

 fjord and towards the Troms Island is mostly built of slaty 

 minerals, such as glimmer-slate (interspersed with crystalline 

 chalk), quartz, sandstone-like slate, &c. Such minerals might 

 have been greatly subjected to being ground away during a 

 longer transport, and that travelled blocks of this kind are not 

 found might be ascribed to this circumstance ; but among the 

 travelled blocks strewn over the Central European high plateau 

 there are found also many of slate, which are supposed to have 

 been transported thither from Scandinavia, and if these have 

 been able to resist the destruc ive agencies during such a long 

 transport, they would decidedly have done so here where the 

 distance is so short. 



Among the softer minerals forming the mountains from the 

 Balsfjord there frequently occur strata of harder nature, as, for 

 instance, of gneiss, massive amphibolites, and eclogites, while 

 Saussurite appears in the bottom of the fjord. There are minerals 

 whose composition would enable them to resist the severest 

 destructive agencies even during the longest journey. The total 

 absence of foreign travelled blocks on Ris Island and adjacent 

 holms is therefore hardly to be reconciled with the supposition 

 that continuous streams of ice froa the inland moved thither. 

 Neither is moraine drift met with about the archipelago in 

 question. 



Juit north of the Ris Island, the Sandviks Island, 407 m. in 

 height, rises above the sea. Along the whole eastern side 

 extensive accumulations of sand containing marine shells are 

 met with to a height of 63 m. In the higher-lying layer the 

 : and is, however, poor in such remains, although fragments may 

 be found at an elevation of 56 m. Here it seems as if the coast 

 districts must have been earlier denuded of the local glaciers of 

 the post- Glacial period than the upland behind. Along the 

 Troms Island and the adjacent district the shell-bearing layer of 

 sand is never found above 13 m., while in the clay deposits 

 along the rivers fossil shells are never found at a higher eleva- 

 tion than 38m. The Troms Islmd has, however, at a time 

 when the sea in relation to the rock was 40 m. higher than at 

 present, been greatly covered by local glaciers, while the coast 

 district beyond must have been almost free from such. The 

 conditions for the development of a more copious fauna of niol- 

 lusks have thus existed along the outer coast earlier than in the 

 fjords behind. It appears therefore that during the transition 

 from the Glacial to the post-Glacial period the milder climate 

 has spread from the sea coastwards, although, as it seems, very 

 slowly. 



We now turn to the district behind the channel referred to 

 particularly to the little Troms Island, where there has been 

 special opportunity of examining these indications. The island 

 is 11 km. long and 157 m. in height, and, lying just in the flow 

 of the ice-stream, was situated so that the travelling glaciers 

 should have left lasting traces on it. By a cursory glance the 

 glaciah t is led to believe that the markings must be referred to 

 the streams of inland ice, particularly as the island is all aloiw 

 the southern part, at higher as well as at lower elevations 

 covered with a layer of drift from the "ground" moraine 

 several feet in thickness, while old boulder drift-wolds may be I 

 seen in several places. Besides this, foreign travelled blocks are | 

 strewn in great numbers along the sides of the island, while stris I 



appear in many places along the littoral belt and adjacent levels. 

 A closer examination will, however, put these indications in a 

 different light. Thus, with regard to the boulder drift, it will 

 be found that most of the stones and blocks embedded in the 

 same belong to the island itself, and none can with certainty be 

 asserted to have belonged to mountains beyond the island. 

 These drifts must therefore be ascribed to local glaciers, which 

 at one time partly covered the island. With regard to the 

 striae, which appear in some places at lower levels,' I am of the 

 opinion that they were made in what is at present the littoral 

 belt. Foreign travelled blocks, i.e. those consisting of various 

 species of granite, are, as stated, only found here at low levels, 

 viz. from the present seashore to an elevation of 38 m. 

 These blocks have, however, I believe, been transported thither 

 by floating glaciers. The elevation, even, in which they are 

 found, indicate that the transport of these foreign blocks can 

 only have begun at a period when the more continuous layers of 

 inland ice were broken up. 



The district along the Balsfjord is, on the other hand, to a great 

 extent built of the same kind of crystalline slate rocks which form 

 the Troms Island, and it is therefore impossible to deny with 

 certainty that there are boulders in the drift which have 

 been carried from the land behind. But there is another 

 circumstance which I believe will make this point plainer still. 

 Between the minerals of the district around the Balfsjord there 

 is, as stated above, also a stratum of Saussurite gabbro, which 

 at the bottom of the fjord is of enormous thickness. The 

 Sau-surite gabbro is a remarkably tough rock, especially qualified 

 to resist the destructive agencies under a long transport. Should 

 therefore a continuous stream of ice at one time have moved 

 forward along this fjord and its bottom, there seems every 

 reason to assume that fragments of Saussurite gabbro would 

 have been carried with it and now be found along its track, 

 which should particularly be the case with the Troms Island, 

 more advantageously situated for receiving the same than any 

 other spot. But in spite of the most careful search the scientist 

 has not succeeded, either between the loose, solitary blocks or in the 

 Glacial drift here, in discovering a single fragment of Saassurite 

 gabbro. There is, therefore, every reason to assume that the 

 ice-streams wdiich moved down the Balsfjord cannot have reached 

 the Troms Island. 



If this conclusion be correct, traces of the Balsfjord ice-stream 

 will not be found along the channels outside, i.e. north of 

 Tromso, viz. neither in the Kval Sound nor in the others in 

 which the ice moved to the sea. There has not been any 

 opportunity of proving this, but from impressions during my 

 frequent journeys along these inlets, I can with confidence assert 

 that no travelled blocks will be found here either whose birth- 

 place was on the upland behind. 



A few years ago I examined the greater part of the mouth oi 

 the Balsfjord, and I have neither there observed travelled 

 blocks which were transported from the bottom of the fjord. 1 

 have therefore come to the conclusion that the continuous ice- 

 stream of the Glacial period cannot have reached beyond the 

 basin of the fjord. 



From the premises thus set forth we may draw the deduction, 

 that the inland ice in North Norway during the Glacial age 

 did not move forward along the above-described line, viz. through 

 the sounds to the ocean, while we may presume that neither did 

 they (ravel through the Balsfjord. 



By the foregoing line of argument the conditions of Northern 

 Norway must have differed greatly from those which we assume 

 prevailed in Southern Scandinavia under the Glacial period. 

 These two deductions, so much at variance, lead to the following 

 conclusions: (1) That either the Glacial period must have 

 appeared in a far severer form in the southern than in the 

 northern part of the peninsula, or (2) that the conclusions here 

 arrived at are based on an erroneous construction of the evidence 

 presented to us. 



With regard to the first of the points, I have already pointed 

 out that every sign seems to indicate that somewhat similar con- 

 ditions prevailed throughout the Scandinavian peninsula during 

 this period. If thus the inland ice in Northern Norway was 

 not powerful enough to move to the ocean along the sounds, 

 there is but little probability of the conditions having differed in 

 this respect in the southern part. And if, on the contrary, this has 

 been the case in the southern half i>f the peninsula, there is every 

 reason to suppose that it was so also in Northern Norway, and 

 that ice has moved coastwards, scouring the surface wherever the 

 depth permitted. It seems, therefore, necessary to assume that 



