On Some Valleys, Terraces and Moraines in the Bergen District, Norway

On Some Valleys, Terraces and Moraines in the Bergen District, Norway

33 ON SOME VALLEYS, TERRACES AND MORAINES IN THE BERGEN DISTRICT, NORWAY. By HORACE WOOLLASTON MONCKTON, TRRAS. L.S., F.G.S. (Read Tanuary 3rd, 1913.) I.-THE VALLEY OF THE FJlERLANDS FJORD 33 II.-SKJOLDEN AND THE LYSTER FJORD 37 1II.-VIK EIDFJORD 42 IV.-SIMODAL 44 V.-THE StiR FJORD AND THE SANDVEN LAKE 45 VI.-THE VALLEY OF THE GRANVIN LAKE 47 VII.-NoRHEIMSUND AND TOKAGJELET 49 I.-THE VALLEY OF THE FJLERLANDS FJORD. N my Address to the Association in 1903 I explained that the I present surface of the Bergen District may be divided into-- I. An oldest land surface, now the high plateaux. 2. The Palseic Surface, an adaptation of Dr. Reusch's term palceiske ouerfiate. 3. The Fjord Valleys, this term to include both the part of the valley now below the sea and also the part of the same valley or system of valleys which is now above the sea-level. The valley in which the Fjserlands Fjord lies, together with valleys at its head, Boiumdal and Suphelledal, belong accord­ ingly to the class Fjord-valleys. During our Excursion of 191 I (see References, 19 I 2, pp. 47-51) we spent three nights at Mundal (see the Map, Fig. 3), and visited the Boium Valley with its glacier, and the Suphelle Valley, with the first of the two glaciers which flow into it (No.3 on the Map, Fig. 3). Some of our party also mounted to the top of the Frudalsbrre, a small snow-field on the mountains to the east of the fjord. The large dotted area in the upper part of Fig. 3 represents a part of the great snow-field Jostedalsbrse. There is a walking route across the snow from the Boiumdal to the arm of the Jolster Lake, shown in the left upper corner of the map-the path descending near the Lunde Glacier marked I. The foot of the Boium Glacier is 492 ft. above the sea, and is 4 Yz miles from the end of the fjord. The remanii part of the Suphelle Glacier is 171 ft. above the sea and 4 miles from the fjord. The rock on both sides of the fjord is in many places ice-marked, the lines running in the direction of the valley, FROe. GEOL. Assoc., VOl. XXIV, PART I, 1913.J 3 34 HORACE WOOLLASTON MONCKTON ON showing that they are the work of a glacier travelling down it, and there can be no doubt that in quite recent geological times the glaciers of Boiumdal and Suphelledal advanced, joined at the '. .' ':.,: ~up'ke/ie'0 ,,> '...'..: -'.i' .. IYlpa' , •. ' ,'. ll('<~~~ '.' . '.':' ~ .:'.~~'~,.:" :,~>~~, :.':-:.:. ,~~ :: ...: ... ~ . .'",,. ..;;:"<'2: ...,., ,.~ "~ /":,,_,,, : .. - ":.:,• "- .• •" II :t , I ~. , " .. , I I' I ,; ,,":',--,' . I , r « » I .". ~ -., , ~~--- .. ~: , , ,.., .........._.:,--, ~ .,.I , , • Il." .... :"".. .. .. ....,,:..,---"'\ , '. ., , " , -' . \ ' . .. , ,...-. I'• . t ".' •..' •,, .. f. ~-- :'.: ~ ~,~ .. - ;' \. ' .. ~- -.. 'fr:lfcl.a/§ ..:. " \',. bra13·.... ~ -, " .... •• ". 1 ,".. .. ~. I ,. - I' 5 ...-- ,1ff1~1 . .;....., o 1 4 6/J1/les FIG. 3.-I\IAP 0[' THE COUNTRY AROUND THE HEAD 0[' THE FJtERLANDS FJORD, r. The Lunde Glacier. 4, The Little SupheUe Glacier. 2. The Boiurn Glacier, 5. The Bjaastad Glacier. 3. The Suphelle Glacier. The dolled areas are snow-fields. place where the valleys meet, and formed a great glacier which moved down the fjord. We consequently have here an area from which the ice has retreated in very recent times, SOME VALLEYS, ETC., IN THE BERGEN DISTRICT. 35 The Boium Valley may be divided into three sections: 1. The Alluvial Flats. 2. Terraces. 3. Valley with moraines. 1. The Alluvial Flat.-A view of the head of the Fjrerlands Fjord, by Mr. Tunbridge, will be found in the Report of our Excursion (References, 1912, Plate 9). The continuation of the valley in which the fjord lies is the Suphelledal, whilst the Boiurndal turns to the left between the houses and the high mountain shown in the view. Deep water extends almost to the head of the fjord, 43 fathoms being marked on the map less than a mile from the shore, which crosses the centre of the view. On the shore at low water we see a sandy flat, which ends under water with a steep slope. The sand is brought down by the river from the two valleys, and deposited when the deep water is reached, so that the land is constantly, if slowly, gaining on the water. The sand extends a little above high-tide level, and we then get a grass-covered flat with water-channels and with many blocks fallen from the side of the valley. We next come to hay­ fields, and farther on to cultivated land, with farms, houses, and trees, the ground, though flat, gradually rising from the fjord. As will be seen in Mr. Tunbridge's view, the Alluvial Flat crosses the whole width of the fjord-valley, and, consequently, extends across the mouths of both the Suphelle and the Boium valleys. The river from the latter valley crosses near the foot of the high mountain, is joined by the Suphelle river, and the united stream enters the fjord near the right side of the view (see the Map, Fig. 3). The material of this flat is, as I have said, brought down by the rivers, and may in part come direct from the foot of the glaciers, but is mainly derived from the sand and gravel terraces in the second section of the valley. 2. Terraces.-As soon as we pass the houses shown on the left of Mr. Tunbridge's view we enter the present section of the Boium Valley, and about a mile from the fjord we find a series of step-terraces which extend up the valley for about a mile and a-half. A view of one of these terraces will be found in our Report (op. cit., Plate 5). The mountain in the centre is the eastern'wall of the fjord-valley. On the left a small glacier is seen. It hangs on the side of the valley but does not descend farther than is shown in the view. The terrace of sand and gravel crosses the middle of the view, and on it we see a farm. If we mount up on to the terrace we find ourselves on a flat with fields and other farms, the flat having a slope towards the fjord Similar terraces at various levels will be seen from the farm, all having a slope towards the fjord. The elevation of the land in this area in late-glacial times has been already dealt with in our PROCEEDINGS (see References, 1912, pp. 36, 37), and I believe that these terraces were deposited in the fjord, their present elevated position being due to rise of the land and consequent retreat of the fjord down the valley. They are formed of moraine HORACE WOOLLASTON ~ONCKTON ON material from the foot of the ice, and are, in fact, terminal moraine spread out in the water in front of the ice. Sections in them consequently show sand and gravel with boulders, but, unlike a terminal moraine deposited on land, they are stratified. The terraces were formed much as the alluvial-flat is being formed now, but they were nearer to the ice and more closely connected with it than the alluvial-flat which is mainly com­ posed of debris washed by water from the older deposits. 3. Moraines.-The terraces end some two and a-half miles from the fjord. Probably the glacier filled the bottom of the valley down to this point until sufficient elevation had taken place to raise the locality above sea-level. The result is that from here onwards the retreating glacier has left more or less regular terminal moraines in the place of stratified terraces. About half a mile beyond the last terrace there is a large moraine of sand and gravel, with big blocks j I believe it to be some 300 ft. above the sea. Then we come to a desolate tract, swept, I believe, by snow avalanches during the spring. We pass other masses of moraine material, and, finally, at the head of the fjord-valley, we see the glacier. The view (Reference, 1912, Plate LA) was taken from a point about a mile from the foot of the ice, and shows the moraine mounds at the houses in the fore­ ground. Mr. Tunbridge's photograph (Plate I.B) shows other moraines nearer to the ice. Some remarks on the variation of length of this glacier in recent times have been given in our PROCEEDINGS (Vol. XXIII, p. 12). It has been advancing during the last few years, and in July, 1912, I noticed that in consequence of the advance its freshest moraine in one place rested on grass, and that Ranunculus and Lotus corniculatus were in flower only 30 ft. in front of the ice foot. The Suphelle Valley.--As I have said, the valley shown at the head of the fjord ill Mr. Tunbridge's photograph (References 1912, Plate 9) is the Suphelle. The foot of the Suphelle Glacier is the white patch at the bottom of the valley in the view. There are many conspicuous moraine mounds in front of it. A part of one is shown in another view (op. cit. Plate IO.B). The valley above the glacier is narrow, and there are piles of debris due to post-glacial falls all along it. The head of the valley is shown in Plate S.A of the same volume where the Little Suphelle Glacier (No.4 on the map, Fig. 3) is seen descending into the valley from the left (western) side. The bottom of the valley is covered with moraine material, the blocks in which are larger when one comes to walk amongst them than might be expected from the photograph.

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