Carrick Island in Larrybane Bay, with a limestone headland, and Rathlin Island in the background, on the North Antrim Causeway Coast Way, County Antrim, Ulster, Northern Ireland, United Kingdom Europe

A climber makes her way up a steep and difficult route on the limestone cliffs in the Aveyron region, near Millau and Toulouse, south west France, Europe

A climber makes her way up a steep and difficult route on the limestone cliffs in the Aveyron region, near Millau and Toulouse, south west France, Europe

Carrick Island in Larrybane Bay, with a limestone headland, on the North Antrim Causeway Coast Way, County Antrim, Ulster, Northern Ireland, United Kingdom, Europe

Dry stone wall, farmers' fields and a copse of trees, Limestone Way, Monyash, Peak District National Park, Derbyshire, England, United Kingdom, Europe

Snack plate with bacon, salami, gray cheese and horseradish on the Rossalm, Braies, Sexten Dolomites, South Tyrol, Italy, Europe

Bonifacio with its limestone cliffs in the foreground

Tourist on suspension bridge over gorge in rugged limestone rocks, limestone rocks in Tsingy de Bemaraha National Park, Madagascar, Africa

Neolithic, megalithic Tarxien Temples, UNESCO World Heritage Site, Paola, Malta, Europe

The entrance to Daugbjerg limestone mines near Viborg, Jutland, Denmark, Europe

Chang Cave, stalactite or limestone cave in karst rock formations, Vang Vieng, Vientiane, Laos, Indochina, Asia

Weltenburg Abbey, the Danube Gorge between Kelheim and Weltenburg, rocks, Danube River, Bavaria, Germany, Europe

The entrance to Daugbjerg limestone mines near Viborg, Jutland, Denmark, Europe

Inside Daugbjerg limestone mines near Viborg, Jutland, Denmark, Europe

Cheese transporter passing narrow tunnel to the Monsted, Monsted limestone caves near Viborg, Jutland, Denmark, Europe

Wooden path, travertine terraces of Pamukkale, UNESCO World Heritage Site, Denizli, Turkey, Asia

Footpath to the Castle Hill Limestone Rocks, Kura Tawhiti Conservation Area, Selwyn District, South Island, New Zealand

Trail through the limestone formations of Castle Hill Limestone Rocks, Kura Tawhiti Conservation Area, Selwyn District, South Island, New Zealand

Limestone rock on the panoramic trail to the Kampenwand peak, Upper Bavaria, Bavaria, Germany, Europe

Cave explorer forces his way up through a narrowing in the rock in a cave high in the White Mountains on the island of Crete.

Three cave explorers tackle a steep rubble slope on their way to an underground camp in a cave in the jungle of Mulu called Whit

A cave explorer pushes his way through a tight section of cave

Cave of Harpea, anticlinal formed in limestone, Basque Country, Pyrenees, France