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Speleology
Seven kilometers north of Krossbu you find Dummdalen. This valley has its name from the stream Dumma. This name can be interpreted either as "the roaring one" or "the dumb one" which may seem strange. But this stream is in fact both roaring and silent. Ever since the inland ice lay thick over the mountain the river Dumma has found its way through the limestone rich bedrock, creating passages and cavities.
Caves can be created in different ways. The largest systems are created in areas where the bedrock consists of sedimentary rock such as limestone. Slightly acidous water finds its way down through cracks in the rock, dissolving the limestone and creating cavities and tunnels on its way down. The minerals in the dripping water are at the same time building up dripstone formations. If the roof caves in, deep depressions in the ground, so called dolines, are created and can grow into valleys.
The result here is a valley full of caves. Some are dry, sometimes high up on the valleyside, and haven't had any real streams in them since the ice age. Others are on the valley floor, letting Dumma continue its work. Some of the caves look like regular pipelines while others are full of fallen down rocks. In addition, there are systems that are only accesible with diving equipment.
In these caves there isn't much of stalagmites (on the floor) or stalagtites (from the roof) to talk of. Instead there are very nice formations where the streaks of limestone have been washed away leaving only the harder parts of the rock. These formations, filled with shining pearls of condensation, are also very pretty to look at.
Depending on which caves you are planning to visit, different equipment is neccessary. Some you can manage without any equipment at all but most of them require a sturdy raindress that isn't easily torn and a torch or even better, a headlamp. A helmet is of course not bad, but you can manage nicely with just a thick cap for protection when scrubbing your head. Liquid is no concern since Dumma has the finest water in the area.
Walk description
The recommended route is to start down at Bøvertun and take the walk up through Dummdalen and over the mountain back home. The simple reason for this is that the caves have a rising level of excitement the higher up you get and it is more fun to start lightly and build up than the other way around. You also get more out of the caves if you aren't tired and worn out by several hours of walking.
When you arrive at Dummdalen from the road just south of Bøvertun you see cave one at once, marked with a big white G1. By following the white-dotted path up through the valley you come to G2, G3, G4-5 and G6. G7, or The Spiral of Death as it is called by the students at Olympiaskolan, isn't marked, but still quite easy to find.
G1
G1 entrance:
N 61°37.800
E 08°02.969
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The first cave can be passed through without a raindress or torch, but you need high boots. It was used as a bridge over Dumma by the old road through Breiseterdalen. Note among other things the pointed boulder hanging wedged in the roof just inside the opening on the left hand side.
G2
G2 entrance:
N 61°37.777
E 08°02.404
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Here both crawling and climbing is neccessary. You get quite dirty and you have the stream roaring below you all the time. There are exit holes both here and there, don't go up to early.
G3
G3 entrance:
N 61°37.771
E 08°02.167
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This cave is like balm for the ears after G2, all quiet. Right in the start is a small pool which, if I have read the speleologists' map correctly, leads through sifons to the great underwater system. If you're a group going into this cave, you should let those with claustrophobia be the last in so they can turn around if neccessary. Here you crawl through a pipeline, long ago created by the stream, and in the middle there is a passage that is like a little keyhole you need to get through. It ends with a small room with exits in many directions. The further you get and the narrower the exit you manage to pass through out to the daylight, the more points you get.
G4-5
G4 entrance:
N 61°37.761
E 08°02.081
G5 entrance:
N 61°37.753
E 08°02.031
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These are two different entrances ending up in the same hall. The G5 entrance is the more comfortable of them and leads down through a rather large sloping room to a passage where you have to crawl over large boulders. Then you get into the big hall that slopes quite steeply downwards. The floor is covered with large boulders to step on and after a while you are accompanied by the stream again.
To get to the bottom of the cave you need to get passed the stream which is easy if you are careful or get a supporting hand. Sometimes though, the torrent is so strong that it isn't advisable to pass. Once over you continue down along the right side of the stream to the pool at the end. This is another of the entrances for those diving. There is a good ledge here to sit on, turn off the lights and let the roar from the stream get the advantage for a while. When you are done philosophizing you take the same way out, perhaps with a detour through the G4 entrance.
G6
G6 entrance:
N 61°37.710
E 08°01.884
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This is also called The Phantom Cave since it has a wide opening, a spacious hall and a veil of running water in front of the opening. It is the perfect lunch place in case of bad weather since the daylight gets in. There is a small brook in here with fresh water and so much space that you can light a fire if you like. It is however quickly explored since the opening that led further inside has caved in.
G7, The Spiral of Death
G7 entrance:
N 61°37.637
E 08°01.544
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After G6 you go down to the path again and follow it up to a small lake. Here you leave your backpack and make yourself ready for the most exciting of the caves of Dummdalen. The opening is situated high up on the valley side south of the lake and there are no white dots showing the way. Cross Dumma where it runs into the lake and walk up the high "steps" on the other side. Then keep to the right and walk along the long ledges up there and look for the hole up to the left. Look for a way to get to the cliff wall and find the entrance.
The entrance is a hole about one and a half meter in diameter that you reach with a small ladder. The hole goes 6-7 meters in before it turns 90 degrees to the left and then continues parallell to the valleyside in a small decline. You crawl almost all the time, but it's not very narrow. Even though there is no running water here it is still quite muddy. By and by it gets steeper downwards, ropes and ladders are in place where you need them. The end of the cave is a downwards spiral that turns 540 degrees before you reach a small room at the bottom, complete with a small brook running straight out of the wall.
For those who want a challenge there are two down here. Two small holes by the floor form the start and finish of a small, very narrow horseshoe-shaped passage. There is also a wider opening into a chimney. In there you can see the sky straight up and with some eqiupment you can climb all the way through the almost ten meters long chimney. The only problem is that you have a waterfall in your head all the way and when you reach the opening you see that it is lined with rocks and boulders that are just waiting for someone to touch them so they get to throw themselves down the hole. In other words, the same route back for those with any instinct of self-preservation.
G8 and onwards
There are more caves. In addition, Dumma is constantly changing the mountain even though the change is slow. Some entrances are opened, others cave in and are closed. The seven that are described here are relatively safe, well visited by tourists and camp schools. If you look for your own caves you have to be careful. The mountain is very prone to falling into pieces and you can't be sure that someone has been there before to pull down the loose stones.
Crystal valley:
N 61°37.197
E 08°00.131
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The journey over the mountain begins with a visit in the Crystal valley. This little passage is white-grey from all the quartsite in the bedrock.
The crossing:
N 61°36.004
E 07°59.195
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After a while's walking along the desolate shores of Svarttjørna you turn up the slope towards Turru and all the other small lakes west of Krossbu. It can be a bit tricky here to see where you should go. Take it easy and keep a lookout for the markings. It is especially easy to miss the crossing with the path that branches off to Nufsvatnet. Here the GPS coordinate can be a good help.
The edge:
N 61°35.641
E 08°01.468
Krossbu:
N 61°34.444
E 08°01.965
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If you have had a long and interesting day in the caves it is probably evening time now as you reach Breiseterdalen again. If you are lucky with the weather letting the sun shine freely on Smørstabbtindane you should absolutly take a rest here at the edge and watch the play of the light on the snow and the steep walls on the other side. When your soul is full you just carry on down the path and out onto the old road up to Krossbu. Length of the walk, appr. 11 km.
Route: DUMMDALEN
G1 entrance: N 61°37.800 E 08°02.969 G1
G2 entrance: N 61°37.777 E 08°02.404 G2
G3 entrance: N 61°37.771 E 08°02.167 G3
G4 entrance: N 61°37.761 E 08°02.081 G4
G5 entrance: N 61°37.753 E 08°02.031 G5
G6 entrance: N 61°37.710 E 08°01.884 G6
G7 entrance: N 61°37.637 E 08°01.544 G7
Crystal valley: N 61°37.197 E 08°00.131 CRYSTAL
The crossing: N 61°36.004 E 07°59.195 TURRUCROSS
The edge: N 61°35.641 E 08°01.468 THEEDGE
Krossbu: N 61°34.444 E 08°01.965 KROSSBU
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Seven kilometers north of Krossbu you find Dummdalen. This valley has its name from the stream Dumma. This name can be interpreted either as "the roaring one" or "the dumb one" which may seem strange. But this stream is in fact both roaring and silent. Ever since the inland ice lay thick over the mountain the river Dumma has found its way through the limestone rich bedrock, creating passages and cavities.
Caves can be created in different ways. The largest systems are created in areas where the bedrock consists of sedimentary rock such as limestone. Slightly acidous water finds its way down through cracks in the rock, dissolving the limestone and creating cavities and tunnels on its way down. The minerals in the dripping water are at the same time building up dripstone formations. If the roof caves in, deep depressions in the ground, so called dolines, are created and can grow into valleys.
The result here is a valley full of caves. Some are dry, sometimes high up on the valleyside, and haven't had any real streams in them since the ice age. Others are on the valley floor, letting Dumma continue its work. Some of the caves look like regular pipelines while others are full of fallen down rocks. In addition, there are systems that are only accesible with diving equipment.
In these caves there isn't much of stalagmites (on the floor) or stalagtites (from the roof) to talk of. Instead there are very nice formations where the streaks of limestone have been washed away leaving only the harder parts of the rock. These formations, filled with shining pearls of condensation, are also very pretty to look at.
Depending on which caves you are planning to visit, different equipment is neccessary. Some you can manage without any equipment at all but most of them require a sturdy raindress that isn't easily torn and a torch or even better, a headlamp. A helmet is of course not bad, but you can manage nicely with just a thick cap for protection when scrubbing your head. Liquid is no concern since Dumma has the finest water in the area.
Walk description
G1
Here both crawling and climbing is neccessary. You get quite dirty and you have the stream roaring below you all the time. There are exit holes both here and there, don't go up to early.
G3
These are two different entrances ending up in the same hall. The G5 entrance is the more comfortable of them and leads down through a rather large sloping room to a passage where you have to crawl over large boulders. Then you get into the big hall that slopes quite steeply downwards. The floor is covered with large boulders to step on and after a while you are accompanied by the stream again.
To get to the bottom of the cave you need to get passed the stream which is easy if you are careful or get a supporting hand. Sometimes though, the torrent is so strong that it isn't advisable to pass. Once over you continue down along the right side of the stream to the pool at the end. This is another of the entrances for those diving. There is a good ledge here to sit on, turn off the lights and let the roar from the stream get the advantage for a while. When you are done philosophizing you take the same way out, perhaps with a detour through the G4 entrance.
G6
This is also called The Phantom Cave since it has a wide opening, a spacious hall and a veil of running water in front of the opening. It is the perfect lunch place in case of bad weather since the daylight gets in. There is a small brook in here with fresh water and so much space that you can light a fire if you like. It is however quickly explored since the opening that led further inside has caved in.
G7, The Spiral of Death
The entrance is a hole about one and a half meter in diameter that you reach with a small ladder. The hole goes 6-7 meters in before it turns 90 degrees to the left and then continues parallell to the valleyside in a small decline. You crawl almost all the time, but it's not very narrow. Even though there is no running water here it is still quite muddy. By and by it gets steeper downwards, ropes and ladders are in place where you need them. The end of the cave is a downwards spiral that turns 540 degrees before you reach a small room at the bottom, complete with a small brook running straight out of the wall.
For those who want a challenge there are two down here. Two small holes by the floor form the start and finish of a small, very narrow horseshoe-shaped passage. There is also a wider opening into a chimney. In there you can see the sky straight up and with some eqiupment you can climb all the way through the almost ten meters long chimney. The only problem is that you have a waterfall in your head all the way and when you reach the opening you see that it is lined with rocks and boulders that are just waiting for someone to touch them so they get to throw themselves down the hole. In other words, the same route back for those with any instinct of self-preservation.
G8 and onwards
