The Coastal Road (State Highway 17) from Holandsfjorden to Nesna
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The coastal road (state highway 17) from Holandsfjorden to Nesna 93 Locality 39 - Blokktinden, Tjong On the road to Tjong and onwards to Reppa there is a good view towards Blokktinden and its very large avalanche cone. Blokktinden is carved in granitic gneiss and belongs to one of the Precambrian basement windows. Strong vertical jointing in the bedrock is one of the reasons for the large quantities of scree material which have accumulated here. The main shore line forms a break in the avalanche slope and can be seen as a horizontal line. Here it represents the marine limit and is clearly developed in the fallen material. This means that most of the cone is a little older than the last part of the Younger Dryas. Probably most of the stoneblocks fell from the mountain wall a little after the mountain emerged from the ice masses 12,000-11,000 years ago. The climate during the first part of Younger Dryas time was very cold which enhanced fracturing of the rock walls and initiated stone-block production. Blokktinden with its 400 m avalanche cone, looking south from Tjong. Photo: Terje H. Bargel. 94 Locality 40 - Nordværnes On a branch road, about 15 km from Straumsvika and only a few hundred metres from Nordværnes, is a body of peridotite (olivine/pyroxene rock). It is easily seen because of ifs reddish yellow alteration colour. Parts of this body, particularly the marginal zone and intersecting veins, are very special. In a groundmass which consists mostly of orthopyroxene there are olivine crystals 5 cm to 1 m in length and randomly orientated. The rock is igneous, but the special texture is the result of alteration processes (metamorphism). Landscape with ochre-coloured weathered peridotite at Nordværnes. Blokktinden (locality 39) in the background. Photo: Terje H. Bargel. 95 96 Locality 41 - Ferry trip Jektvika -Kilboghamn (60 min.) The ferry quay at Jektvik lies approximately where the glacier margin of the inland ice lay 12,300 years ago (see map page 93). It is thought that the marginal zone crossed Åsen (202 m above sea level) southwest of Jektvika. From the ferry we can see Rødøyløva to the northwest, with its characteristic island profile in which the uppermost part of the mountain ridge resembles the head of a lion. Rødøyløva consists of red, granitic gneiss. Other islands to the west are Renga and Rangsundøy which consist partly of granitic gneiss, partly of altered sedimentary rocks such as micaceous gneiss and marble. After passing Telnes there is a good view of Melfjorden to the east. The ferry crosses the Arctic Circle here. The glacier margin crossed Melfjorden 12,300 years ago (A-glacier margin line, see map page 22). The route of the ferry between Jektvik and Kilboghamn may have been ice-free as early as 12,300 years ago. The fjord was probably full of icebergs at that time and the only 'tourists' who visited the area must have been whales or other marine animals. In Nordfjorden, a branch of Melfjorden, there is a permanent seal colony today. This is a protected area. Locality 42 - Kilboghamn At Kilboghamn there are also indications of the glacial margin 12,300 years ago. just south of the ferry landing (800 m} there is a gravel pit opened in a glacial marginal deposit with large transported blocks on its surface. This deposit is thought to represent the A-glacier margin. From Øresvika we can see eastwards and inwards to Gjervalen which is the innermost arm of Sørfjorden. About 10,000 years ago thick tongues of ice extended down to the fjord, 3-6 km from Øresvika. 97 98 Map of the ice situation 10,000 years ago. Two glacial tongues from the inland ice extend down to the fjord and icebergs drift in the sea outside the ice margins, filling parts of the fjord basin. This is in sharp contrast to the situation prevailing today. 99 Locality 43 - Tonnes After passing 0resvika one can take a 15 km long side road to Tonnes before returning to, and continuing on the main road. From Tonnes there is a good view of a cave on the mountain side to the northeast. This cave lies about 100 m above sea level. Many fallen blocks and much rock cover the rocky threshold at the opening. The cave is 170 m long and must have been excavated and shaped by the sea. It follows the contact between mica-schist and banded gneiss which is parallel to the strike direction of the gneisses here. In the sand on the floor of the cave aluminium sulphate has been found. In former times this was used by the local population for tanning leather. 100 From Tonnes there is a good view of Hestmannen (Hestmona). From the shipping channel this feature looks like a man riding a horse (hest), therefore the name. It can also be seen from highway 17 when driving along the northeast side of Aldersundet. Hestmannen consists of mica- schist, but the smallest of the two summits is granitic. Hestmannen seen from Kvaroya. Locality 44 - Aldersundet The nearest island on the west side of Aldersundet is Aldra, its highest summit being 967 m above sea level. It consists for the most part of granitic gneiss, but there is a belt of mica-schist and marble in the low ground where the houses are located. A marked shore line is carved in thick till and is about 90 m above sea level. Above the sports ground in Aldersundet, about 1 km from the road, there is a marginal moraine deposited outside one of the many cirque glaciers of Younger Dryas time. This cirque glacier extended down to the sea level at that time. This is about 90 m above the present level which corresponds to the marked shore line on Aldra. 101 The strandflat seen from Grønsvika fort (fortress). 102 The Træna islands seen from the east. Notice the almost flat-lying layers of gneiss in Trænstaven (to the right in the picture, 336 m a.s.l.), and also the contrast between the strandflat and the high mountains (relics of erosion). Photo Terje H. Bargel. Island domain to the west From Stokkvågen the ferry and express boat service goes to the islands to the west, including Lurøya, Lovunden and Træna. The islands consist of the same rocks as those on the mainland, i.e. gneisses and mica schists of Precambrian and Cambro-silurian age, Younger sedimentary rocks which make up most of the continental shelf are not present on the islands. Several islands rise above the strandflat and have characteristic topographic profiles. Lovunden (623 m above sea level), is well known and has a colony of puffins living in the scree on the north side: The mountains of Træna, including .Trænstaven (336 m above sea level) lie on the Island of Sanna, At the foot of the mountains there are several caves and rock surfaces developed when the sea level was higher than it is today. The most well known of these is Kirkhelleren where excavations have revealed traces of settlement in several periodes from both the Older and Younger Stone Ages and from the Iron Age. 103 Locality 45 - Grønsvika fort Viewing point. Parking at cafe. The fortress was in use during World War II. It is now being restored as a historical site from that time. The rock is a greyish white, quartz-feldspar-rich gneiss. It is of Precambrian age and belongs to the Sjona window. From the highest point within the fortress there is a view westwards to Lovunden, Lurøy and the distinctive strandflat. Locality 46 - Bogen Stopping place towards the sea at Silavågen. The rock at this place is the usual, light-coloured, pinkish, bed-rock gneiss in the Sjona window. It consists of red feldspar, grey quartz and black hornblende as well as a little magnetite. These minerals are also present in small irregular pegmatites (coarse-grained intrusive rocks) and are easy to identify. Locality 47 - Flostrand Stopping place in former quarry, about 3.5 km west of Flostrand. The rock is a grey, hornblende-bearing basement gneiss. In the gneiss there are several light- coloured pegmatite veins. In connection with some of these veins there is a network of cracks. The cracks are filled with sulphide-bearing minerals and ankerite, CaFe(CO3)2. Weathering of these minerals gives the gneiss a rusty appearance for half a metre or so from the veins. The veins themselves are only a few decimetres wide. A narrow, dark, biotite-rich vein can be seen in the road-cut. This follows the planar structure in the gneiss and is similar to that in the previous locality, an altered diabase dyke. During the deglaciation 10,000 years ago there was a fjord connection between Sjona and Ranafjorden via Utskarpen. This lasted several thousand years, but 5,000-6,000 years ago the land uplift had progressed so far as to close the fjord connection and cause the Utskarpen area to be dry land. 104 105 Locality 48 - Sjonfjellet View point from the stopping place just below the former cafeteria. In good weather this is a very good view point. Lovunden and Træna can be seen far out to sea and to the north, and northeast there is a view to the almost naked terrain of the granite areas on the opposite side of Sjona. This shows how important the composition of the rock is for the vegetation. In the mountain side to the south a sharp boundary can be seen. This is considered to be the thrust boundary for the Helgeland nappe complex which is the uppermost nap-pe unit preserved in the Caledonian mountain chain.