3 Types of Rock for Climbing: Granite, Sandstone & Limestone

The Geology of Rock Climbing

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Climbing on mountains, cliffs, and pinnacles on the earth’s surface give rock climbers the opportunity to be intimate with the earth’s surface, with the erosion-resistant parts that compose the rugged landscapes which attract climbers, including buttes, mesas, cliffs, crags, towers, spires, and mountains of all sizes. All of these earth forms are composed of different types of rocks, each of which tells a different story about the history of the earth.

Rocks come in all kinds of forms, compositions, and hardnesses from soft shale to hard granite. Climbers by their intimacy with rock usually become interested in geology.

3 Main Types of Rocks

Rocks are composed of various minerals—inorganic elements and compounds that each have a characteristic chemical composition, crystal form, and distinct physical properties. Some common minerals found in rocks include quartz, feldspar, biotite, muscovite, hornblende, pyroxene, and calcite. There are three main types of rock found: igneous, sedimentary, and metamorphic rocks.

Different Rocks for Climbing

While geologists are concerned with how rocks were formed, what their mineral composition is, and how they weather, climbers and mountaineers are more concerned with the rock properties that lend themselves to climbing. These include the hardness of the rock; the handholds and footholds which occur; and the shapes that the rock weathers into.

Different types of rock form different sorts of formations that allow for different types and styles of climbing. The following are three of the most commonly encountered rock types that climbers encounter in the United States.

Granite Forms Many Climbing Areas

Granite is an igneous rock, the basic building block of all of the earth’s land surfaces and mountains.

Granite, which occurs in various forms, originates when large pockets of magma, molten rock that lies deep within the earth’s surface, slowly cools and hardens below ground surface. Granite is a fairly coarse-grained rock with high contents of quartz and feldspars that are generally very hard and resistant to erosion. Because of its hardness, granite often forms large rock masses which are weathered by wind, rain, snow, and ice into mountains, cliffs, and domes. Weaknesses in granite that erosion attacks are generally vertical joints which widen into cracks, so many of the best crack climbs are found on granite cliffs.

Best Granite Climbing Areas

Granite forms many of the best American climbing areas, including Yosemite Valley, Tuolumne Meadows, Joshua Tree National Park, Longs Peak and Rocky Mountain National Park, Black Canyon of the Gunnison, the South Platte region, and the White Mountain cliffs, including Cathedral Ledge, Whitehorse Ledge, and Cannon Cliff in New Hampshire.

Sandstone: Rock for Crack Climbing

Sandstone is a sedimentary rock, a rock type that encompasses a wide variety of characteristics and is deposited directly on the earth’s surface. Roughly 75% of the earth’s land surface is covered with some type of sedimentary rock.

Sedimentary rocks like sandstone form when minute rock particles, often from granite, are deposited by wind and water on earth surfaces. The piles of sediment are then compressed by the weight of overlying debris and cemented together by water which slowly percolates through the particles, precipitating minerals which help cement and harden the new rock over millions of years.

Sandstone is layered, with new layers deposited atop older ones which form a sort of tiered cake structure. Each layer represents different terrestrial environments when the rock was originally deposited. Many sandstones, such as those found in the desert around Moab, Utah, were deposited in ancient sand dune fields, while others were deposited along receding beaches or in swamps and river deltas.

Sandstone Rock Climbing Areas

While sandstone is easily eroded, fragile, and usually soft, it also forms excellent terrain for rock climbing with great friction qualities as well as vertical joints or fractures which crack for climbers.

Some of the major sandstone climbing areas in the United States includes Indian Creek Canyon, the Moab area, Zion National Park, Red Rock National Conservation Area, and the Garden of the Gods.

Limestone: Perfect Sports Climbing Rock

Limestone, another type of sedimentary rock, forms under different circumstances than sandstones. Limestone, forming about 10% of the world’s sedimentary rocks, are formed underwater in ancient coral reefs and from shells and skeletal fragments of living organisms. Living reefs are diverse and unique, qualities which form different kinds of limestones which provide different kinds of climbing experiences. Limestone is composed of aragonite and calcite, forms of calcium carbonate, silica, as well as very fine water-borne sediment like clay, silt, and sand. Limestone is usually very well cemented, forming a hard durable surface for climbing, and is generally erosion resistant so it forms long cliff bands. Limestone slowly dissolves in acid, including rainfall which is naturally acidic, hence most American limestone cliffs have fewer solution pockets than those in Europe. Limestone forms vertical and overhanging cliffs, which are perfect for sports climbing, as well as caves.

Great Limestone Climbing Areas

Some of the major American climbing areas composed of limestone are Shelf Road, Rifle Mountain Park, American Fork Canyon, and Mount Charleston and other areas around Las Vegas.