Cairn
A small pile of stones used as a trail marker. See also Monument and Duck. Cairns are often used in canyon country to mark the location of trails and hiking routes. Cairns, especially over slickrock areas, are normally placed at intervals along or at places where a route makes a turn.

Caldera
A large, bowl-shaped volcanic depression with a diameter many times greater than the included volcanic vent or vents. It may be formed by explosion or collapse.

Caliche
A solid, almost impervious accumulation of which calcium carbonate-rich material commonly found in layers on or near the surface of soils in arid regions.

Cap Rock
A hard rock layer capping a softer rock unit (such as basalt capping a soft sandstone).

Carapace
The upper part of a tortoise or turtle shell.

Carnivorous
Subsisting on nutrients obtained from the breakdown or animal tissue.

Casual
A species that has appeared in a given area somewhat more frequently than an accidental, but whose normal range is in another area.

Caudal
Pertaining to the hindmost part of the body; tail.

Cave
A natural cavity, recess, chamber, or series of chambers and galleries beneath the surface of the earth, within a mountain, a ledge of rocks, etc.

Cavates
Ancestral Puebloan dwellings dug out of soft tuff cliff walls, creating small caves suitable for living. Pronounced CAVE-eights.

Cerro
Spanish for hill.

Chaparral
Brushy areas where plants such as manzanita, cliff rose, scrub oak, and ceanothus are the dominant plants.

Check Dam
A line of stones stacked to block a small wash, creating a small pool of water and accumulating fertile sediments.

Chert
A sedimentary rock composed of extremely fine-grained quarts, formed by organic or inorganic precipitation or by replacement. Flint and jasper are varieties of chert.

Chockstone
A rock or boulder wedged into a narrow canyon.

Chrysalis
The naked pupa of a butterfly.

Cinder Cone
A conical hill formed by the accumulation of volcanic ash or cinders around a vent.

Cirque
The steep walled bowl carved by glacial action at the head of a side canyon.

CG
Campground

Claim Post
A post or rock monument used to mark the boundary of a mining claim.

Clastic Rock
A sedimentary rock that is made up of fragments of preexisting rocks, transported mechanically into the place of deposition.

Clay
An extremely fine-grained, natural sediment or soft rock composed of particles less than 4 microns.

Cliff
A high, steep face of rock; a precipice.

Cliff Dwelling
Stone ruin built into the side of a cliff.

Clutch
The total number of eggs laid during a single nesting period; some birds lay several clutches in a nesting season.

Cocoon
Protective case of many larval forms that surrounds the pupa; silky or other covering formed by many animals for their young.

Col
A saddle or gap across a ridge or between two peaks.

Colony
An aggregation of individuals with some degree of organization in a community, normally of one species.

Community
An association of living things, plant and animal, each occupying a certain position or ecological niche, inhabiting a common environment and interacting with each other.

Composite Cone
A volcanic cone composed of both lava and pyroclastics, often created by a series of cyclic eruptions in which pyroclastics are created by explosive eruptions until the vent is open, then lava flows occur. Most large continental volcanic cones are this type.

Concretion
An accumulation of mineral matter, formed when particles of silica, pyrite, gypsum, etc. become cemented together into an orderly, rounded, often artificial-looking form.

Conglomerate
A sedimentary rock consisting of boulders and cobbles set in a finer-grained matrix.

Conifer
A cone-bearing, usually evergreen tree or shrub.

Contour
A line connecting points of equal value on a map or diagram, most commonly points of equal elevation on a map. When hiking, especially when bushwhacking, following the natural contours of a ridge or slope makes the climb much easier, although often much longer.

Convertible Tent
Convertibles are hybrid tents that come with pole, window, vestibule, and/or rainfly options so you can strip down the tent for casual summer trips or strengthen if for stormy adventures.

Couloir
A steep, relatively narrow groove in a rock wall. Typically, couloirs are wider than "cracks" and smaller than "gullies," and are important as routes up the mountainside.

Country Rock
The rock enclosing a mineralized vein or the rock surrounding and intruded by an igneous body.

Crampons
A set of metal spikes which are strapped to the boots to provide secure footing on steep ice or consolidated snow.

Creeper
Technically, a trailing shoot that takes root at the nodes; but can denote any trailing, prostrate plant.

Cross-bedding
A sequence of beds inclined at an angle to the main bedding planes in granular sediments.

Cross Country
Traveling across terrain without a trail.

Cup Nest
A nest built or woven in a cup shape.