Glossary

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 Alluvial Fan - most commonly found in desert and semi-arid environments. The lack of vegetative protection in drylands allows infrequent, heavy rains to flush large amounts of rock debris down slopes. It is this transported material, or alluvium, that makes up an alluvial fan. A fan is formed as a mountain stream, loaded with sediment, rushes through a steep, deeply cut valley and then spills out onto an open plain. At the canyon mouth, the rapid water flow suddenly slows down and spreads out, losing kinetic energy and the ability to carry sediment. With this loss of energy along the lower grade mountain front, the stream dumps its load. The coarsest debris is deposited first, closest to the canyon mouth. Finer sediments are transported further away from the apex and deposited at a distance. Even large boulders can be transported downhill by water and scattered over an alluvial fan. Bangs Field Trip

Basal- (when referring to plants) leaves that originate and attach at the base of the plant. Mesa Plant Slides 

Cactus- a plant with a thick surface and prickly, needle-like leaves, which grows primarily in hot and dry regions. Bangs Field Trip 

Catkins- A spikelike flower cluster that bears scaly bracts and petalless, unisexual flowers. Mesa Plant Slides 

Conifers - plants that produce their seeds in cones and usually have needle shaped leaves. Bangs Field Trip| Mesa Field Trip 

Crust- the outermost layer of rock on the earth. Mesa Field Trip 

Cross-stratification- When ripples move over the sediment surface, and have time and space to deposit sediment, their passage is recorded by the development of cross stratification. As the ripple advances downstream, sand grains roll up the upstream side and collect on the ripple crest. When they get too heavy, they avalanche down the downstream face of the ripple. This motion produces a sediment layer that is oriented at an angle to thesediment bed. The resultant deposit is said to be cross-stratified. Mesa Field Trip 

Cryptobiotic Soil- Cryptobiotic soil is made up of minute bacteria that form a sticky substance which holds grains of sand together and slows erosion. The organisms in the soil absorb large amounts of water which helps nearby vegetation to survive. In addition, the nitrogen-fixing capabilities of the organisms in cryptobiotic soil create fertilizer that can be used by plants. Cryptobiotic soils form very slowly and if damaged or destroyed will not be replaced within our lifetimes. This produces the right setting for erosion. Fewer healthy plants will be able to survive in areas where these soils have been destroyed and erosion has taken place. Bangs Field Trip 

Desert Varnish- A thin dark shiny film, composed of iron oxide with traces of manganese oxide, formed on the surface of pebbles, boulders, and rock outcrops in desert regions after long exposure. Bangs Field Trip 

Erosion- the wearing away of soil and rock by weathering, mass wasting, and the action of streams, glaciers, waves, wind, and groundwater water. Bangs Field Trip 

Forbs- herbaceous plants other than grasses, sedges or rushes; examples of forbs are clover, thistle and sage. Bangs Field Trip 

Grasses- plants having narrow leaves and jointed stems. Bangs Field Trip 

Hoodoos- independently standing rock outcroppings. Mesa Field Trip 

Igneous Rock- rock formed by solidification from a molten magma. Bangs Field Trip| Mesa Field Trip 

Invertebrates- animals lacking a backbone or spinal column. Mesa Field Trip 

Lava- molten rock which erupts or flows from an active volcano. Mesa Field Trip 

Lava Rocks- the rock formed after lava has cooled and hardened. 

Magma- molten rock underneath the earth's surface. Mesa Field Trip 

Mantle- the solid rock found just below the crust. Mesa Field Trip 

Metamorphic Rocks- Any rock derived from pre-existing rocks by mineralogical, chemical, and/or structural changes. Bangs Field Trip 

Montane- related to mountains. Mesa Field Trip| Mesa Plant Slides 

Outcrop- an exposed section of a geological formation. Mesa Field Trip 

Pediment- a broad, gently sloping erosion surface or plain of low relief, typically developed by running water. Mesa Field Trip 

Pegmatite Dike- exceptionally coarse-grained igneous rock that has crystallized in cracks or voids in an existing geologic structure. Bangs Field Trip 

Petroglyphs- man-made rock carvings. Mesa Field Trip 

Precipitation- the amount of water that falls in the form of rain, snow, sleet or hail. Mesa Field Trip 

Quake- to shake or tremble. Mesa Plant Slides 

Riparian Zone- the area found along banks of rivers and streams. Bangs Field Trip| Mesa Field Trip 

Sedimentary Rock- a rock resulting from the consolidation of loose sediment that has accumulated in layers. Bangs Field Trip 

Seine- a large, weighted fishing net.Mesa Field Trip 

Sessile- leaves are directly attached to the branch; leaves lacking petioles 

Shrubs- woody plants that grow close to the ground and have several stems beginning at its base. Bangs Field Trip 

Slumping- a landslide that is caused when a mass of rock becomes saturated with water and slides downward. Mesa Field Trip 

Subalpine- Subalpine forest extends from the twisted, windblown limber pine at treeline through the dense, moist fir and spruce forests to the lodgepole pine and aspen at lower elevations. Residents include chipmunks, ground squirrels, chickaree, pine marten, porcupine, bobcat, black bear and elk. Mesa Field Trip| Mesa Plant Slides 

Spike- the top of the plant containing seeds. Mesa Plant Slides 

Talus slope- a steep, concave slope formed by the accumulation of loose rock fragments. Mesa Field Trip 

Terraces- a large bench or step-like ledge that is horizontal or gently sloping. Mesa Field Trip 

Toe- the downslope edge of a landslide or slump. Mesa Field Trip 

Transpiration- loss of water vapor by land plants. the rate of transpiration can be affected by changes in environmental conditions such as an increase in temperature, wind speed or a decrease in relative humidity. Bangs Field Trip 

Unconformity- A break or gap in the geologic record, such as an interruption in the normal sequence of deposition of sedimentary rocks. Bangs Field Trip 

Understory- the vegetation lying beneath a canopy (or covering) of taller trees; also called the shrub layer. Bangs Field Trip 

Waste Rock- valueless rock that must be removed in mining. Bangs Field Trip