A look at some major rock types decorating Colorado

Sandstone

We associate this with the reds and oranges we see at Garden of the Gods, Roxborough State Park and Colorado National Monument. On the browner side, the Flatirons are also of the rock falling into the category of sedimentary. That refers to stone formed on or near the Earth’s surface.

GraniteThe mighty, gray rock is synonymous with Colorado’s highest mountains and most mesmerizing canyons. It’s most famously showcased by sheer, vertical faces. Granite, such as Pikes Peak’s and Rocky Mountain National Park’s, is igneous rock — formed by the cementing of cooled magma.

LimestoneClimbing meccas Shelf Road and Rifle Mountain Park are composed of this rock that tends to provide crimped edges and overhang ceilings. Limestone is sedimentary rock composed of calcium carbonate (calcite) and the double carbonate of calcium and magnesium (dolomite).

BasaltThe town sharing the name of the rock can provide something of an education. Basalt was christened for the formation coating a mountain in view: columns that represent volcanic flows frozen solid. Many of these formations are seen around the San Juan Mountains in the southwest.

GneissYou’ve got examples of sedimentary and igneous rock. Gneiss (pronounced “nice”) is of the third major category: metamorphic, referring to rocks that have been altered within the Earth’s crust and now feature multicolored layers and bands, such as those at Black Canyon of the Gunnison.

— seth boster