To answer your last question: it's not really calculated like that. The only criterium is that snow survives: be it 1, 2 or 10-years old. It doesn't matter. In 1996, the snow at Garbh Choire Mhor was (I think) around 20-years old when it did go.
How long do they have to have stuck around to be classed as permanent or even a small ice cap?
I picked a book up somewhere about the Cairngorms, it was quite old (1960's i think) and it had a picture of Coire an Snaechda on Cairngorm and under it a caption said something like "a view of the britains only glacier in coire an snaechda". Is this true, was there once a small glacier there,
ps sorry for any dodgy spelling.
I think I know the book/pic you are referring to and the the pic is of Coire an Lochain. Very occasionally a spring avalanche on the Great slab in that coire produces what looks like a small glacier in the coire with a huge depth of snow and deep crevasses forming. Certainly it looks just like a glacier in the pic I saw!
Of course it is not a real glacier, for that form properly you need about a 150ft depth of neve to compress the snow into ice.
Snow Patches Surviving on Scottish Mountains
in Spring Weather Discussion
Posted
I think I know the book/pic you are referring to and the the pic is of Coire an Lochain. Very occasionally a spring avalanche on the Great slab in that coire produces what looks like a small glacier in the coire with a huge depth of snow and deep crevasses forming. Certainly it looks just like a glacier in the pic I saw!
Of course it is not a real glacier, for that form properly you need about a 150ft depth of neve to compress the snow into ice.