Most popular rock type for climbing by number of ascents 2010-2019
Limestone
Limestone is carbonate sedimentary rock composed of the skeletal fragments of ancient marine organisms. Owing to the UK's geological history, limestone is a very prevalent rock type in the UK. As limestone slowly dissolves in acid, including rainwater which is naturally acidic, the resultant water-solution pockets in limestone provide excellent hand- and finger-holds in addition limestone is often very well cemented, forming a hard durable surface perfect for sport climbing, traditional climbing, or bouldering.
Slate
One rock type that is seldom found outside of British rock climbing is slate. Virtually impermeable to water, and easily split into tiles, slate became a very desirable roofing product. In 1890, the industry peaked with over 17,000 men employed in the mines and quarries of North Wales. The eventual decline of these industries lead to vast swathes of abandoned anthropogenic rock exposures. The popularity of this rock type in the North Wales climbing community followed shortly after. Most of the existing routes are still there in their original style and many have become sought-after traditional classics. More recently the area has been developed with a multitude of difficult sport routes from short single pitches to almost 'big-wall' multi-pitch routes.