Double Dihedral?

I was thinking the other day, so we're already in uncharted territory.

It occurred to me that I've never seen a double dihedral. As in, there are two cracks and it's almost a different route or at least mirror image of itself depending on which shoulder you scum.

I think this would be extremely rare because of the way cleavage lines go and because gravity tends to remove heavily fractured rock. It's got to exist somewhere. Has anyone come across it?

Like this?

near the start...

No, not at all.

I'm talking a dihedral with two cracks. What you've posted is actually two dihedrals. Really common on volcanic rock.

I don't want to do an MS paint picture. Just imagine one dihedral with two cracks.

Not a great photo, but like this?

Me, on Carey Corner, shortly after falling and hitting the ledge because my belayer couldn't see me. It was a short fall though.

Mike, from that angle, your second picture looks spot on to what I'm imagining. Is it like that the whole way? Is it almost 2 climbs depending on which crack you take?

From the bottom:

Looking up Carey Corner

The double crack starts right when the dihedral begins. The dihedral is formed by a very large partially detached block. As you suggest, gravity seems to have taken care of the bottom half of that block.

The crack on the right is fists to OW. At the grade (CT 5.7...so like 5.8+?) the climb uses both cracks at once. Either crack on it's own is probably significantly harder.

The double crack isn't in the photo, but this climb has a pinched/incipient crack on the right face in the corner. It opens up to finger size for some of the climb. It's not really used for climbing, but it takes pro.

Pika's Paradise dihedral

Good examples. I wonder if I've come across one before and haven't noticed. I can't think of any though.

Soler on Devils Tower has this type of feature. See:

As a matter of linguistics, why is a single dihedral with two cracks a double dihedral?

What about Crynoid Corner at Shelf Road? There are two cracks that continue the each plane created by the dihedral. Not perfectly symmetric, but definitely two cracks at right angles, in the same dihedral.

mountainproject.com/v/10853…

On a complimentary note: The double arete problem at Morrison is worth checking out. I have yet to complete it.
mountainproject.com/v/doubl…

Does this count? Twin Cracks

How about this?

rgold wrote:As a matter of linguistics, why is a single dihedral with two cracks a double dihedral?

By that measure, is a dihedral without a crack called a slab?

It's a testament to my memory how many of these routes I've actually climbed yet couldn't recall that I'd ever been on a double dihedral.

As to the name, I made it up. You could call it whatever you like. I try to stick with simple descriptive terms.

rocknice2 wrote: By that measure, is a dihedral without a crack called a slab?

No. A dihedral means "two planes." There doesn't have to be (and in terms of the geometry should not be) a crack along their line of intersection. It's still a dihedral.

And if there are seventeen cracks in and around it, all arranged in two planes, then its still a (single) dihedral.

Thanks for clearing that up for me.

Maybe we could call it an ambidextrous dihedral.

Isn't a double dihedral a chimney?

rocknice2 wrote: By that measure, is a dihedral without a crack called a slab?

The Rad Sporto crowd would probably call it a splitter corner.

A dihedral with two cracks enabling the climber to grapple up either side.
Is called a 'Bihedral'.