# UKC

## / inside corner

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Can someone tell me what an American climber means by an ''inside corner''?

A normal (open book) corner as opposed to an arête (aka outside corner).

> A normal (open book) corner as opposed to an arête (aka outside corner).

When I open a book I get both a corner and an arete.

But the one facing you isn't normally the arête!

It seems that in the early days of rock climbing in the UK (up to about the time of the first ascent of Cenotaph Corner), the term 'corner' was often used for something we'd now call an arete. Like the corner of house. E.g Birchden Corner, North-West Corner (at Harrisons) and Congo Corner at Stanage. The implication is that the Americans still use the term in both senses.

Americans use the terms "book", "inside corner" and "dihedral". I wonder what the differences are. Interestingly, there is an American asking in another thread what the difference is between a corner and a groove!

Post edited at 11:14

I think its as simple as corners tend to be 90 degrees and close to vertcal and traditionally were used for outside and inside versions, in the UK as well as the US, as Gordon correctly points out. Grooves tend to be more than 90 degrees and anything from slabby to overhanging but can be anything angle-wise from where flared chimneys end to something barely perceptable (but still usable by a skilled ascentionist).

PS wonderful point on an open book ...takes a mathematical mind to look at a book that way.

Post edited at 11:49

My perception of a groove is that it is a vertical gouge out of the rock that could be rounded or angular and probably doesn't have a crack in the back. A corner (inside) always has a crack in the back however thin it may be. A corner is usually formed where the rock is jointed a groove can be in a solid piece of rock even a slab.

Post edited at 11:51

> I think its as simple as corners tend to be 90 degrees and close to vertcal

But there are some nowhere near vertical, e.g. Hammer and Agony on the Etive Slabs.

I  know of one climb which is actually an arete, but has Corner as part of its name. Proud Corner (VS 4c)

Post edited at 20:35