On 14/05/2010 Olbert wrote:
>The only way to train for Frog is to go to a dolomite cliff - no sandstone comes close.
The nerdy geologist in me has to point out that Frog is made of dolerite, not dolomite. Dolomite is a magnesium rich carbonate rock formed in the ocean (similar to limestone). Dolerite is an igneous rock that cools from a molten state close to the earth's surface. The shallow cooling depth of the dolerite causes it to contract forming regular columns (similar to the polygonal joints seen in dried out mud). The gaps between the columns sometimes form heavenly cracks (ahhh).
Anyone who has climbed in both the Dolomites, Italy and Frog buttress (or Ben Lomond, etc. etc.) will know how different these two rock types are.