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Why are all the mountains in the alps pointy and all the mountains in this country not?
In reply to Anonymous: Because they are still in nappies, while ours are OAPs.
In reply to Anonymous: They were formed a lot later in the geological timescale, and are therefore, as Dave says, babies, compared to our mountains which have been eroded into more rounded shapes over millions of year.
In reply to Anonymous:
Glaciation, matey, glaciation. How can they let people into universities these days without GCSE geography?
Glaciation, matey, glaciation. How can they let people into universities these days without GCSE geography?
In reply to Anonymous:
I believe it's because mountains in the Alps were, in geological terms formed fairly recently. Mountains in this country are much older and so have been subject to more weathering, erosion etc creating a more rounded appearance (eg. Skiddaw is the oldest mountain in the Lakes and is shaped like an upturned pudding bowl).
I'm sure the geology police will tell me I'm totally wrong about all this, however!
I believe it's because mountains in the Alps were, in geological terms formed fairly recently. Mountains in this country are much older and so have been subject to more weathering, erosion etc creating a more rounded appearance (eg. Skiddaw is the oldest mountain in the Lakes and is shaped like an upturned pudding bowl).
I'm sure the geology police will tell me I'm totally wrong about all this, however!
In reply to Graham:
How can they able to tell the ages of the mountain?? cut off and count the ring?
How can they able to tell the ages of the mountain?? cut off and count the ring?
In reply to CragHead: Depends how pointy they are....
Strewth.
Strewth.
In reply to Graham Cumming:
I'm no geologist and this is a genuine comment/question - surely you're not suggesting that our mountains had their tops rounded by galciers - I know they're small compared with, say, the Alps but surely they would have been higher than most of the glaciers?
> (In reply to Anonymous)
> Glaciation, matey, glaciation. How can they let people into universities these days without GCSE geography?
> Glaciation, matey, glaciation. How can they let people into universities these days without GCSE geography?
I'm no geologist and this is a genuine comment/question - surely you're not suggesting that our mountains had their tops rounded by galciers - I know they're small compared with, say, the Alps but surely they would have been higher than most of the glaciers?
In reply to CragHead: It's a mere toddler compared to ranges such as the Lakes and the Highlands, I believe the Himalayas are even younger.
To answer your question more seriously: God knows - but i think it has something to do with continental shifts. But fundamentally, I ain't got the foggiest.
To answer your question more seriously: God knows - but i think it has something to do with continental shifts. But fundamentally, I ain't got the foggiest.
In reply to CragHead: Yes, and in 350 million years it'll be about the size, and shape, of Cairngorm.
In reply to CragHead: It is isn't it. The Alps are 'falling down' at an alarming rate due to the general warming of our climate and ferocious glacial retreat.
Get out there soon, they won't be there long!
Get out there soon, they won't be there long!
Essentially, all amswers are correct. In order of age....oldest first
Scottish Highlands (Caledonian orogeny)
Alps (Alpine orogeny)
Himalaya (Himalayan orogeny)
It's all about erosion, whether through glaciation or otherwise.
The Highlands may once have rivalled the Himalaya in terms of height but have since been eroded. Of course, the alps and Scotland are "dead" and merely eroding. However, the Himalaya are still active in that mountain building has not quite stopped ie. the Indian continental mass is still decellerating as it ploughs into the Asian continent.
Scottish Highlands (Caledonian orogeny)
Alps (Alpine orogeny)
Himalaya (Himalayan orogeny)
It's all about erosion, whether through glaciation or otherwise.
The Highlands may once have rivalled the Himalaya in terms of height but have since been eroded. Of course, the alps and Scotland are "dead" and merely eroding. However, the Himalaya are still active in that mountain building has not quite stopped ie. the Indian continental mass is still decellerating as it ploughs into the Asian continent.
In reply to JonC: Scotland's hills are just a big plateau that got chopped up by glaciers. The Highlands are a range of glens,the hill s being the surviving land.
Unfortunately the plateau was just over 3000' with a few higher bits (Monadh Ruadh, Ben) and this has given us Munro Bagging.
While not as macho as an ongoing orogeny (ooh err Missus) this type of hill can get quite good, ie Norway, Spitzbergen and Greenland.
And there are still some spikey things in Scotland.. Trallval, Cir Mhor, Gillean and friends. Sadly these are out numbered by all the Geal Charns.
Unfortunately the plateau was just over 3000' with a few higher bits (Monadh Ruadh, Ben) and this has given us Munro Bagging.
While not as macho as an ongoing orogeny (ooh err Missus) this type of hill can get quite good, ie Norway, Spitzbergen and Greenland.
And there are still some spikey things in Scotland.. Trallval, Cir Mhor, Gillean and friends. Sadly these are out numbered by all the Geal Charns.
In reply to Fat Bumbly: I am sory but b*llocks! The scotish mountains were formed in a ginormous continental collison and were at their peak propably an awful lot higher than the himalya. to give you an idea of scale here; the calidonides (the mountain chain formed in the caledonian orogony) extends from south wales up through scotland before branching east to spitzburgen and the northeast of scandinavia and west through greenland, newfoundland and all the way down the north apalation mountains in the usa! There was about 500 million years of erosion before the glaciers even started to form.
In answer to the question about were the mountain tops glaciated in the uk: some of them were, around Glencoe you can see glacial terracing on the higher peaks which shows the level of the surface of the glaciers (although ice sheeet would be more accurate) those hills whose summits are below that level are characteristically much more round implying that the ice did go over the tops.
In answer to the question about were the mountain tops glaciated in the uk: some of them were, around Glencoe you can see glacial terracing on the higher peaks which shows the level of the surface of the glaciers (although ice sheeet would be more accurate) those hills whose summits are below that level are characteristically much more round implying that the ice did go over the tops.
In reply to thespacecat:
Pointy birds,
A pointy A pointy,
Anoint my head,
Anointy Anointy.
Soz, could resist
Doug
Pointy birds,
A pointy A pointy,
Anoint my head,
Anointy Anointy.
Soz, could resist
Doug
In reply to thespacecat:
Yes but they are very young mountains created from volcanic explosions only 55 million years ago. Give it another 400m years and it'll be like the South Downs up there!
> Apart from the Cuillin of Skye, which are very pointy indeed.
>
>
Yes but they are very young mountains created from volcanic explosions only 55 million years ago. Give it another 400m years and it'll be like the South Downs up there!
In reply to Anonymous:
I heard somewhere that the Cuillins and the Torridon range (Liatach etc) are the oldest mountains in the world. Does anyone know if this is true????????????
I heard somewhere that the Cuillins and the Torridon range (Liatach etc) are the oldest mountains in the world. Does anyone know if this is true????????????
In reply to Paul Sykes:
Well the cuillin is volcanic while torridon is sedimentary so I guess they both can't be the oldest. I thought that the malverns in worcestershire was some of the oldest rock in the UK... but then I know nothing.
Well the cuillin is volcanic while torridon is sedimentary so I guess they both can't be the oldest. I thought that the malverns in worcestershire was some of the oldest rock in the UK... but then I know nothing.
In reply to Paul Sykes:
The Cuillins are the youngest mountains in Britain (see post above). This is reason why they are so jagged.
The Cuillins are the youngest mountains in Britain (see post above). This is reason why they are so jagged.
In reply to Anonymous:
Is it torridon that is the oldest then? One day i will learn all about this stuff it fascinates me
Is it torridon that is the oldest then? One day i will learn all about this stuff it fascinates me
In reply to Paul Sykes:
Torridon is very old but I remember reading that the oldest in the UK are further north (can't remember which hills) with some rocks 2.7 billion years old.
Torridon is very old but I remember reading that the oldest in the UK are further north (can't remember which hills) with some rocks 2.7 billion years old.
In reply to Paul Sykes: Torridonian Sandstone is roughly 1000 M years old, which does make them very old, but certainly not the oldest(don't know what is). Lewisian Gneiss is far older still, and is visible in many parts of NW Scotland, esp around Gruinard Bay, and Poolewe areas.
By comparison the Cuillins dont know they've been born yet!!
By comparison the Cuillins dont know they've been born yet!!
In reply to Anonymous: No f*cking idea .........
In reply to Anonymous:
Thanx guys all has been explained i will stop bugging you all now i have found a site http://freespace.virgin.net/leaf.ltd/geology.htm that clearly explains all this in interesting terms. I'm gonna go study this now....thanx again
Thanx guys all has been explained i will stop bugging you all now i have found a site http://freespace.virgin.net/leaf.ltd/geology.htm that clearly explains all this in interesting terms. I'm gonna go study this now....thanx again
In reply to Ian Straton: Bollocks NOT!
The great range caused by continental collision was worn down to a plateau, this plateau was the one that got carved up, rejuvenating the mountain range.
Far more recently than the 400m year old big range, high mountains were formed by volcanic action in the tertiary.
Big smoking things where Ardnamurchan, Rum , Mull and Skye are today.
These too were cut down to size.
The great range caused by continental collision was worn down to a plateau, this plateau was the one that got carved up, rejuvenating the mountain range.
Far more recently than the 400m year old big range, high mountains were formed by volcanic action in the tertiary.
Big smoking things where Ardnamurchan, Rum , Mull and Skye are today.
These too were cut down to size.
In reply to SimonW: Probably jagged because of the gabbro and the proxiimity to the western coast, where the effects of glaciation are strongest, with ice flowing down off the big central icecap. The 'youth' probably comes into it as the ground would have been higher there once.
Dykes probably help as well, sometimes the basalt is resistant (Inn Pin) and other times it was worn away to form gaps.
The best pointy stuff in Norway is gabbro as well.
Such a shame the Cairngorm granite was not on the coast.. we may have been left with a Sam Ford Fjord to play on. Instead, it was mainly protected under the ice cap and shaped by the corrie glaciers. Still a great place though.
Dykes probably help as well, sometimes the basalt is resistant (Inn Pin) and other times it was worn away to form gaps.
The best pointy stuff in Norway is gabbro as well.
Such a shame the Cairngorm granite was not on the coast.. we may have been left with a Sam Ford Fjord to play on. Instead, it was mainly protected under the ice cap and shaped by the corrie glaciers. Still a great place though.
In reply to thespacecat:
In Dilman's Grove.........
In Dilman's Grove.........
In reply to Ian Straton:
I thought these sort of mountain building events reflected the underlying tectonic plates (easy enough to understand in the case of the Alps - Italy, or rather the plate on which it rides, colliding with the European {Eurasian?} plate). But as far as I am aware, there are no plate boundries close to the UK. Is this true, or have the plate boundries shifted relative to the continental masses overlying them?
I thought these sort of mountain building events reflected the underlying tectonic plates (easy enough to understand in the case of the Alps - Italy, or rather the plate on which it rides, colliding with the European {Eurasian?} plate). But as far as I am aware, there are no plate boundries close to the UK. Is this true, or have the plate boundries shifted relative to the continental masses overlying them?
In reply to Simon: There was an ocean (Iapetus) between most North America and the bit of Europe with England on it.
This closed up somewhere about the Southern Uplands.
When the Atlantic opened up big chunks of what was then North America got left behind in Europe and Svalbard.
I suppose the mountain building took place when the Iapetus Ocean closed up and plates collided. Europe hitting North America, just like India running into Asia. Big Hills!
This closed up somewhere about the Southern Uplands.
When the Atlantic opened up big chunks of what was then North America got left behind in Europe and Svalbard.
I suppose the mountain building took place when the Iapetus Ocean closed up and plates collided. Europe hitting North America, just like India running into Asia. Big Hills!
In reply to Simon: There are the remains of plate boundaries - these are usually referred to as 'sutures' - so the Iapetus suture (which runs roughly down through southern uplands and the Shannon estuary - although this interpretation changes....) reflects the closed plate boundary between the old Avalonia and Laurentia plates.
In reply to Andy Robinson: I thought it was the Great Glen fault marked off where NW Scotland is actually a bit of Newfoundland that got left behind when the Atlantic upwelling broke the continents apart? Mind, this is 20 year old Geology, half remembered, so I may have the wrong bit?
As to the Alps? I thought they were still growing, as Africa is STILL not stopped bumping into Southern Europe? Which also formed the South Downs, IIR?
Old rocks in the UK? Not as old as Lewisian Gneiss, but we have PreCambrian stuff in the Nuneaton ridge, and Charnwood forest, down here in the Midlands. Sadly, they're now mostly M6, and M1...
Tim, TG
Tim, TG
As to the Alps? I thought they were still growing, as Africa is STILL not stopped bumping into Southern Europe? Which also formed the South Downs, IIR?
Old rocks in the UK? Not as old as Lewisian Gneiss, but we have PreCambrian stuff in the Nuneaton ridge, and Charnwood forest, down here in the Midlands. Sadly, they're now mostly M6, and M1...
Tim, TG
Tim, TG
In reply to Fat Bumbly: sorry to reveive this one again but bollocks, bollocks and more bollocks, where do you get this shit from? For a start if you had a flat or undulating plateu how in hell do you get deep valleys from a glacial period? you would not get distinct valleys but a plained off surface witness the germanic plains where the 4 stages of the pleistocene glacial event were identified: completly flat no deep cut glacial valleys at all. glaciers modify existing river valleys, they do not cut their own.
second point there are mountain ranges in the world at least twice as old as the scottish highlands that have not been eroded flat, the megaliesberg in south africa, the klein karoo in south africa, most of canada east of the rockies, the musgrave and macdonald ranges in central australia (of which ayers rock is one) are f*ucking ancient (all of them over 1 billion years old, some of them probably pushing 3 billion years old, the highlands are mere toddlers by comparison!) and still have not been completly flatened!
As for the "big smoking things" will you just piss off! these vocanos were formed as part of the atlantic opening, that means oceanic basalts, 2 things to bear in mind about basalt: 1) it is the least viscous lava going, it doesn't form really big mountain edifices.
2) it is very hard wearing when cooled.
while they have been eroded for sure "cut down to size" is a misnomer, they were never that big to start with! and are probably not that much smaller now hence why they are still "all pointy and stuff".
If you are going to try to be patronising at least try to do some research first.
second point there are mountain ranges in the world at least twice as old as the scottish highlands that have not been eroded flat, the megaliesberg in south africa, the klein karoo in south africa, most of canada east of the rockies, the musgrave and macdonald ranges in central australia (of which ayers rock is one) are f*ucking ancient (all of them over 1 billion years old, some of them probably pushing 3 billion years old, the highlands are mere toddlers by comparison!) and still have not been completly flatened!
As for the "big smoking things" will you just piss off! these vocanos were formed as part of the atlantic opening, that means oceanic basalts, 2 things to bear in mind about basalt: 1) it is the least viscous lava going, it doesn't form really big mountain edifices.
2) it is very hard wearing when cooled.
while they have been eroded for sure "cut down to size" is a misnomer, they were never that big to start with! and are probably not that much smaller now hence why they are still "all pointy and stuff".
If you are going to try to be patronising at least try to do some research first.
In reply to Ian Straton: Sorry if patronising...Just failed humour... I am not taking this too seriously. Sorry, I look forward to the next smokeless Icelandic basalt spewing fissure. Also IIRC Gabro is formed deep down, I would have expected an ash cone or biggish shield over what is now the Cuillin.
But did anyone say anything about vallys being created..
Deepened yes... Ice obeys gravity, I presume, therefore will accumilate in such places.
There was a preceding glen structure.. Ardgour glens along the pattern of big east flowing rivers etc..
Flat is a relative term, but I am not going to be shifted from a disected plateau. You seem to be confusing a worn down range of relatively gentle hills, rejuvenated by glaciation with glaciers turning East Anglia into the alps or Fjords by the Wash.
I need an explanation as to why the Rough Bounds look like the Rough Bounds, and the Glen Affric Hills or Monadh Liath look like the Monadh Liath. Likewise Hardangervidda vrs Hardangerfjord.
Glacial modification of a high plateau works for me, but I am open to new ideas, even if put in an unpleasant fashion.
But did anyone say anything about vallys being created..
Deepened yes... Ice obeys gravity, I presume, therefore will accumilate in such places.
There was a preceding glen structure.. Ardgour glens along the pattern of big east flowing rivers etc..
Flat is a relative term, but I am not going to be shifted from a disected plateau. You seem to be confusing a worn down range of relatively gentle hills, rejuvenated by glaciation with glaciers turning East Anglia into the alps or Fjords by the Wash.
I need an explanation as to why the Rough Bounds look like the Rough Bounds, and the Glen Affric Hills or Monadh Liath look like the Monadh Liath. Likewise Hardangervidda vrs Hardangerfjord.
Glacial modification of a high plateau works for me, but I am open to new ideas, even if put in an unpleasant fashion.
In reply to Ian Straton: Ian,
Please leave the abuse out in your disagreement with Fat Bumbly and stick to the arguments. If (as the rest of your posts seem to indicate), you both have some knowledge about the subject but disagree about the conclusions, advance coherent, rational arguments, not dogmatic assertions liberally sprinkled with abuse. That is sinking to the level of ignorant, intolerant, self-righteous idiots like "Jonno" and should be left to the "half-drunk in a pub and bigotted and prejudiced to start with anyway" political threads. We all know that these are not worth reading, and can avoid them either from their titles, or definitely from their authors. This sort of thread has been quite interesting and well-informed (or has seemed so to me), so please don’t join the Jonnos in an irrational bar-room brawl. Lets leave this sort of thread and those that represent inquires about aspects of mountaineering and climbing as being constructive, intelligent and helpful if possible. Your contribution has been valuable, but you don’t add any greater conviction to your views by sprinkling them with obscenities.
Just to display my ignorance of the subject, how is it that the volcanic events that formed the Lake district were due to Atlantic opening? I thought that the location of that was along the Mid-Atlantic ridge, where Iceland is located. Also, surely most of Canada east of the Rockies is mind-destroyingly flat (the Canadian shield)? I stand to be corrected/instructed on these points.
Please leave the abuse out in your disagreement with Fat Bumbly and stick to the arguments. If (as the rest of your posts seem to indicate), you both have some knowledge about the subject but disagree about the conclusions, advance coherent, rational arguments, not dogmatic assertions liberally sprinkled with abuse. That is sinking to the level of ignorant, intolerant, self-righteous idiots like "Jonno" and should be left to the "half-drunk in a pub and bigotted and prejudiced to start with anyway" political threads. We all know that these are not worth reading, and can avoid them either from their titles, or definitely from their authors. This sort of thread has been quite interesting and well-informed (or has seemed so to me), so please don’t join the Jonnos in an irrational bar-room brawl. Lets leave this sort of thread and those that represent inquires about aspects of mountaineering and climbing as being constructive, intelligent and helpful if possible. Your contribution has been valuable, but you don’t add any greater conviction to your views by sprinkling them with obscenities.
Just to display my ignorance of the subject, how is it that the volcanic events that formed the Lake district were due to Atlantic opening? I thought that the location of that was along the Mid-Atlantic ridge, where Iceland is located. Also, surely most of Canada east of the Rockies is mind-destroyingly flat (the Canadian shield)? I stand to be corrected/instructed on these points.
In reply to Simon: Sorry about that, I was slightly pissed last night and the fat bumblies explaination for the formation/development of the highlands is very badly flawed, the way mountain chains develop and erode just doesn't support the explanation he is putting forward. For example for every metre of rock eroded off of a mountain 66cm is replaced by uplift of the mountain root below the surface, so mountains only decrease in height very very slowly and the 500 million years or so that the highlands have been eroding is not enough time to reduce them to anything like a plataeu, the last glacial period in reality only reshaped pre-existing features it certainly did not carve out the mountains as they are now from any kind of a plataeu. His comment about gabro is also poor, any baslatic edifice would have gabro at it's base, I suggest he looks up "opheolite complex" before making such statements again.
To answer your question about the mid atlantic ridge and the lake district: the lake district volcanic edifice is very much older thatn the atlantic rift, fat bumbly and I were talking about the volcanic sequences that are in the scottish western isles. The modern mid-atlantic ridge is (unsurprisingly given it's name!) in the middle of the atlantic but it initially formed under the continant consisting of a combined europe and north america/greenland, the intial phase of rifting opened the north sea but never actually broke the conitnental crust, seperating the uk from mainland europe, the second phase split the continental crust along what is now the west coast and split ireland from the uk forming the irish sea. It then started injecting magma into the crack, it does this equally on both sides of the rift pushing the land masses apart while the rift itself stays put.
Imagine you are laying a wooden floor with planks of wood, start with two planks next too each other, put a book on top of each (these are your landmasses) now push them apart (the opening is the rift) and put another 2 planks in, repeat, your books very quickly are no longer anywhere near where you are adding the planks but they were at the start, this is why the mid atlantic ridge is no longer anywhere near the british coast. Intrestingly Iceland is not technically a land mass, it consists entirely of ocean floor rock types!
As for canada, I will put my hands up, it was the poorest of my examples! However there are large areas of what are now hills rather than mountains, there are some areas that reach 1000m, given that the interior of canada is one of the oldest sheild areas in the world (second only to australia, and then not by much) it makes a very intresting case study for erosion, the hill ranges there are truly ancient and have probably suffered more erosion than any other mountain chain (because of their latitude and the fact that it is such a massive continental area, they have been over run by many more glacial events and their normal climate is rather harsher than scotlands) and yet there are still hills.
That said it would probably have made more sense to turn the canadian example round and say: if glacial periods carve up and rejuevinate old badly eroded mountains why are the central canadian hils so rounded and undramatic?
see told you I was pissed last night! I hope all of that makes sense.
To answer your question about the mid atlantic ridge and the lake district: the lake district volcanic edifice is very much older thatn the atlantic rift, fat bumbly and I were talking about the volcanic sequences that are in the scottish western isles. The modern mid-atlantic ridge is (unsurprisingly given it's name!) in the middle of the atlantic but it initially formed under the continant consisting of a combined europe and north america/greenland, the intial phase of rifting opened the north sea but never actually broke the conitnental crust, seperating the uk from mainland europe, the second phase split the continental crust along what is now the west coast and split ireland from the uk forming the irish sea. It then started injecting magma into the crack, it does this equally on both sides of the rift pushing the land masses apart while the rift itself stays put.
Imagine you are laying a wooden floor with planks of wood, start with two planks next too each other, put a book on top of each (these are your landmasses) now push them apart (the opening is the rift) and put another 2 planks in, repeat, your books very quickly are no longer anywhere near where you are adding the planks but they were at the start, this is why the mid atlantic ridge is no longer anywhere near the british coast. Intrestingly Iceland is not technically a land mass, it consists entirely of ocean floor rock types!
As for canada, I will put my hands up, it was the poorest of my examples! However there are large areas of what are now hills rather than mountains, there are some areas that reach 1000m, given that the interior of canada is one of the oldest sheild areas in the world (second only to australia, and then not by much) it makes a very intresting case study for erosion, the hill ranges there are truly ancient and have probably suffered more erosion than any other mountain chain (because of their latitude and the fact that it is such a massive continental area, they have been over run by many more glacial events and their normal climate is rather harsher than scotlands) and yet there are still hills.
That said it would probably have made more sense to turn the canadian example round and say: if glacial periods carve up and rejuevinate old badly eroded mountains why are the central canadian hils so rounded and undramatic?
see told you I was pissed last night! I hope all of that makes sense.
In reply to Anonymous:Age.
In reply to Ian Straton: Thanks....
Back to the tertiary..
How did the ring dyke on Ardnamurchan form?. Subsidence of some sort, a caldera? It just looks amazing on a map or aerial photos.
Good climbing on the gabbro as well.
Old hills...
There are some biggish hills east of the Rockies,but I suspect they may related to what ever shoved the Appalachians/Highlands up. 1600m in Labrador, 1200m in Gaspe and the Laurentians. Newfoundland is hilly in places.Gros Morne looks pretty amazing, big fjords in a disected plateau,very Hardanger, but the mouths are > sealevel, like Loch Morar.
Bivouac.com recently featured some impressive Cairngorm like things at the head of some Labrador fjords...
The shield seems to be very relief challenged. Provincial high points are low. 600+m in Ontario, and 800+m for Manitoba. North of the 60th, the high ground is around Ellesmere/Bylot/Baffin and the Mackenzies in the West. Between,the vast low shield.
Saskatchewan bucks the trend getting up to 1300m, but this area may be south of the shield.
There is a lot of old rock to the west, and this forms big ranges like the Purcells. The rocks are old, but big hills like that are probably still being raised.
Back to the tertiary..
How did the ring dyke on Ardnamurchan form?. Subsidence of some sort, a caldera? It just looks amazing on a map or aerial photos.
Good climbing on the gabbro as well.
Old hills...
There are some biggish hills east of the Rockies,but I suspect they may related to what ever shoved the Appalachians/Highlands up. 1600m in Labrador, 1200m in Gaspe and the Laurentians. Newfoundland is hilly in places.Gros Morne looks pretty amazing, big fjords in a disected plateau,very Hardanger, but the mouths are > sealevel, like Loch Morar.
Bivouac.com recently featured some impressive Cairngorm like things at the head of some Labrador fjords...
The shield seems to be very relief challenged. Provincial high points are low. 600+m in Ontario, and 800+m for Manitoba. North of the 60th, the high ground is around Ellesmere/Bylot/Baffin and the Mackenzies in the West. Between,the vast low shield.
Saskatchewan bucks the trend getting up to 1300m, but this area may be south of the shield.
There is a lot of old rock to the west, and this forms big ranges like the Purcells. The rocks are old, but big hills like that are probably still being raised.
In reply to Ian Straton:
Yes, I think it makes sense, though it may take 3 or 4 readings to fully absorb. I am particularly intrigued by the idea of Iceland being technically part of the sea bed - rather like the old description of glass as "a liquid having the external appearance of a solid".
A very vivid metaphor regarding the planks and books. What a fascinating subject, and how incomparably higher the standard of debate is on this sort of discussion than in the political rants.
Yes, I think it makes sense, though it may take 3 or 4 readings to fully absorb. I am particularly intrigued by the idea of Iceland being technically part of the sea bed - rather like the old description of glass as "a liquid having the external appearance of a solid".
A very vivid metaphor regarding the planks and books. What a fascinating subject, and how incomparably higher the standard of debate is on this sort of discussion than in the political rants.
In reply to Anonymous:
The surface of the earth becomes forther from the axis of rotation the closer you get to the equator.
The resultant increase in centrifugal force is what makes the mountains bigger and pointier the closer you get to zero degrees latitude.
The real reason the glaciers on Kilimanjaro are reatreating is that bits keep getting flung into orbit.
The surface of the earth becomes forther from the axis of rotation the closer you get to the equator.
The resultant increase in centrifugal force is what makes the mountains bigger and pointier the closer you get to zero degrees latitude.
The real reason the glaciers on Kilimanjaro are reatreating is that bits keep getting flung into orbit.
In reply to Fat Bumbly: "Saskatchewan bucks the trend getting up to 1300m, but this area may be south of the shield."
its on the shield but with sediment on top. the shield is about 1000m down. i wouldnt call it a mountain, it may be 1300m but the average gradient is 2 degrees or less! more like a high plateau. thats why they call that area the "high plains".
incidentally it is the same sediments, dissected by fluvial erosion and in a drier climate further to the south in the USA that form the famous USA "badlands". course they never got glaciated.
but to answer the original question:
The Alps are pointed, because the Cirque headwalls meet up. The scottish Highlands are not pointed, because the cirques (Ok, corries) did not generally erode back far enough to meet up.
The age of rocks does not indicate the age of the range. For instance: the Columbia Mountains of Western Canada, are composed partially of continental crust of up to 2.1 billion years in age, but the landform (mountains) has only existed since the Eocene, so the mountain range is much less than 1% as old as the rocks which make it up.
its on the shield but with sediment on top. the shield is about 1000m down. i wouldnt call it a mountain, it may be 1300m but the average gradient is 2 degrees or less! more like a high plateau. thats why they call that area the "high plains".
incidentally it is the same sediments, dissected by fluvial erosion and in a drier climate further to the south in the USA that form the famous USA "badlands". course they never got glaciated.
but to answer the original question:
The Alps are pointed, because the Cirque headwalls meet up. The scottish Highlands are not pointed, because the cirques (Ok, corries) did not generally erode back far enough to meet up.
The age of rocks does not indicate the age of the range. For instance: the Columbia Mountains of Western Canada, are composed partially of continental crust of up to 2.1 billion years in age, but the landform (mountains) has only existed since the Eocene, so the mountain range is much less than 1% as old as the rocks which make it up.
In reply to almost sane at a different PC:
Douglas, that is so silly. The real reason is that the alps were flattish till Hannibal started walking elephants over them and made great troughs in the land that got eroded by rain and glaciers.
If you look at places like kinder that had peaks on it once till the industrial revolution when all the mill workers used to walk over it to get to work and flattened it.
all that peat on the top is the mud off their boots from the back alleys they used to get into their houses. Nobody could use the front door except when they were dressed up to go to church.
The highland clearances did you a favour, if they had not happend Bidean would be lower and flattened by highland millworkers doing the same as the Manchester ones. Stanage was 300ft high before they started making steel in Sheffield and took the top off for millstones to grind the knives on.
Now you know.
BTW, why does it snow on Mt Kenya when it is on the equator, so near the sun?
Douglas, that is so silly. The real reason is that the alps were flattish till Hannibal started walking elephants over them and made great troughs in the land that got eroded by rain and glaciers.
If you look at places like kinder that had peaks on it once till the industrial revolution when all the mill workers used to walk over it to get to work and flattened it.
all that peat on the top is the mud off their boots from the back alleys they used to get into their houses. Nobody could use the front door except when they were dressed up to go to church.
The highland clearances did you a favour, if they had not happend Bidean would be lower and flattened by highland millworkers doing the same as the Manchester ones. Stanage was 300ft high before they started making steel in Sheffield and took the top off for millstones to grind the knives on.
Now you know.
BTW, why does it snow on Mt Kenya when it is on the equator, so near the sun?
> its on the shield but with sediment on top. the shield is about 1000m down. i wouldnt call it a mountain, it may be 1300m but the average gradient is 2 degrees or less!
Ideal for that 'Grade I leader' thread...
In reply to sutty: This could explain why Welsh montains are lower than Sottish ones, for sure. All those 'Miners Tracks' on Snowdon, for instance...
As to Mount Kenya, what you have to remember is that because it's on the equator, it actually gets COLDER in the dark? So the snow forms at night, and reflects the heat during the day. It's only the fact that all those wilderbeest pass a LOT of methane, forming the Serengeti Greenhouse, that the whole of Africa isn't a gigantic icefield...
As to Mount Kenya, what you have to remember is that because it's on the equator, it actually gets COLDER in the dark? So the snow forms at night, and reflects the heat during the day. It's only the fact that all those wilderbeest pass a LOT of methane, forming the Serengeti Greenhouse, that the whole of Africa isn't a gigantic icefield...
In reply to Fat Bumbly: Never studied that one personnaly but ring dykes only form in 2 ways: collapse of a magma chamber or caldera collapse, if it is a perfect(ish) circle then more likly to be a caldera collapse as magma chambers tend to be more elongated.
the mountains in Labrador and newfoundland (inc baffin island) are caledonian, they were formed in the same orogeny as the highlands thats why they look quite similar, the fjords are better because canada was glaciated for longer, which incidently is partly why the sheild is so low. If you lookt a relif map of canada there are distinc rings centred around hudson bay, that is because the massive weight of the icesheet squashed the landmass down into the mantle, hudson bay (in common with scotland and the baltic area) is isostaticaly rebounding faster than the rising sea levels, there are some fantastic fossilised, raised beaches up there.
the mountains in Labrador and newfoundland (inc baffin island) are caledonian, they were formed in the same orogeny as the highlands thats why they look quite similar, the fjords are better because canada was glaciated for longer, which incidently is partly why the sheild is so low. If you lookt a relif map of canada there are distinc rings centred around hudson bay, that is because the massive weight of the icesheet squashed the landmass down into the mantle, hudson bay (in common with scotland and the baltic area) is isostaticaly rebounding faster than the rising sea levels, there are some fantastic fossilised, raised beaches up there.
In reply to Dru:
this is a very good point, you do have to be careful about how you date orogenies, fortunatly most orogenies genertate significant volcanic or magmatic activy resulting in igneous intrusions that cut through the preexisting strata, these can be radio dated but even so this is slightly dodgy especially if you are looking at igneous or metamorphic rocks, it is a real minefield, corobarating evidence is usually needed from elsewhere.
I am sure you probably knew that already but for simon (who seems to be developing a burgening intrest in geology) its a point worth noting.
> The age of rocks does not indicate the age of the range. For instance: the Columbia Mountains of Western Canada, are composed partially of continental crust of up to 2.1 billion years in age, but the landform (mountains) has only existed since the Eocene, so the mountain range is much less than 1% as old as the rocks which make it up.
this is a very good point, you do have to be careful about how you date orogenies, fortunatly most orogenies genertate significant volcanic or magmatic activy resulting in igneous intrusions that cut through the preexisting strata, these can be radio dated but even so this is slightly dodgy especially if you are looking at igneous or metamorphic rocks, it is a real minefield, corobarating evidence is usually needed from elsewhere.
I am sure you probably knew that already but for simon (who seems to be developing a burgening intrest in geology) its a point worth noting.
In reply to Ian Straton:
Nope - that would be carbonatite lavas - orders of magnitude less viscous than even the most primitive basaltic lavas.
Plus Iceland contains appreciable amounts of rhyolitic and more intermediate lava types so is not exactly your typical 'ocean floor' landmass.
> 2 things to bear in mind about basalt: 1) it is the least viscous lava going, it doesn't form really big mountain edifices.
Nope - that would be carbonatite lavas - orders of magnitude less viscous than even the most primitive basaltic lavas.
Plus Iceland contains appreciable amounts of rhyolitic and more intermediate lava types so is not exactly your typical 'ocean floor' landmass.
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