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2WD. Vehicle. "Two-wheel drive." Refers to a car, such as a sedan, in which power is only applied to two of the four wheels. Such vehicles are best driven on paved roads and some well-maintained dirt and gravel roads. Many all-wheel drive vehicles belong in this category because of low clearance.

4WD. Vehicle. "Four-wheel drive." Refers to a vehicle, such as a jeep, in which power can be applied to all four wheels and the vehicle body is held high above the ground. Such vehicles are capable of being driven on rough dirt roads, in sandy places, and other such off-highway roads. In most places around southern Nevada, 4WD vehicles are restricted to existing roads and approved routes; they cannot legally be driven off into the bushes and virgin desert.

Abiotic. Biology. Refers to nonliving components of the environment such as rocks, water, and the atmosphere. Compare with Biotic.

Achene. Plant. A small, dry, indehiscent (not splitting open at maturity) one-seeded fruit with a thin shell (for example, a sunflower seed).

Adit. Mining. A horizontal or near horizontal mine opening (note that the term "shaft" refers to a vertical mine opening). In mines, therefore, there are horizontal adits, vertical shafts, and various angled inclines and ramps.

Agave Roasting Pit. Archaeology. A large cooking pit (10-45 feet across and up to 10-feet high) used by native peoples and recognized as doughnut-shaped piles of limestone rocks. Native peoples dug a pit, lined it with limestone rocks, and built a big fire in the pit. When the fire burned down to coals, they scraped the coals to the side, put the food (agave and meat) in the hot bottom of the pit, and covered everything with coals and hot limestone rocks from the edge of the pit. When the food was cooked, they uncovered the food by scraping the rocks and ash to the side. Limestone rocks don't hold the heat after a couple of roastings, so new rocks are constantly added, thus creating the large doughnut-shaped piles.

Alluvial Fan. Landform. A fan-shaped deposit of alluvium on a hillside below the mouth of a mountain canyon where the alluvium spreads out across the hillside and down to the valley floor. Alluvial fans often form the hillside between the steep sides of a mountain and the valley bottom.

Alluvium. Landform. Debris from mountain erosion (e.g., rocks, sand, and gravel) that is moved by flowing water and deposited where the water slows down (e.g., riverbeds, flood plains, and alluvial fans). Alluvium can cover other landforms, and if later eroded, can appear as, for example, a gray cap atop bright sandstone cliffs.

Annual Plant. Plant. Plants that complete the cycle of germination, growth, reproduction, and death in one year (growing season). The species persists from year to year as seeds that can lie dormant for decades. This is a life-strategy for avoiding the heat of the desert summer and for avoiding drought. The seeds of annual plants are an important food source for desert rodents. Compare with Perennial Plant.

Anticline. Landform. A place where layers of rock are bowed up in the middle to create a ridge. See also Syncline.

Aquatic Plant. Plants that live partly or entirely in the water.

Arete. Landform. A thin, almost knife-like, ridge of rock; usually steep.

Ariole. Plant. The area on a cactus stem from which spines, flowers, and leaves arise. Often a raised bump on the surface of the stem.

Association. All the plants and animals that live together in a particular place. Associations are bound together by food webs and other interactions. The concept of “association” implies that members come and go over time as conditions change. Compare with Community.

Backpacking. Carrying a sleeping bag, food, and other gear into the wilderness with the intention of staying out at least one night. Gear typically is carried in a backpack.

Bajada. Landform. A series of alluvial fans (one per canyon) that have coalesced into one larger landform along the side of a mountain or mountain range.

Basal. Referring to the bottom or base of something, as in basal leaves in reference to the lower leaves on a plant or plant stem.

Basalt. Rock. A hard, fine-grained, dark (black), igneous rock that results from the rapid cooling of magma. Basalt often forms the cap on a butte; sometimes cracks to form columnar blocks.

Basin. Landform. A low area of land surrounded by mountains or other higher lands. Desert basins often have a playa in the bottom.

Bedding. Landform. Layers of sedimentary rock that show different grain sizes or compositions. Bedding indicates successive depositional events. See Stratification.

Bench. Landform. Usually a flat, elevated area of alluvial materials in a canyon between the wash and the hillside. Usually, a bench is formed when a wash in a canyon cuts a new channel down through older alluvial materials, leaving the old, flat streambed high and dry. Can be used to refer to any flat-topped area on a hillside, but generally restricted to alluvial benches and benches formed by the wave action of ancient lakes.

Biotic. Refers to living components of the environment such as plants and animals. Compare with Abiotic.

BLM (United States Bureau of Land Management). A branch of the federal government charged with managing wild lands, primarily desert lands. Historically, the BLM focused on leasing lands for cattle, mining, and other extractive uses, but recently it has become more friendly towards the environment and now manages recreational areas as the Red Rock Canyon and Sloan Canyon National Conservation Areas and several Wilderness Areas in southern Nevada.

Butte. Landform. A steep sided, flat-topped hill formed by erosion of the surrounding materials. Buttes are often capped by a resistant rock layer (e.g., basalt) that protects the softer underlying rocks. Buttes are taller than wide; compare with mesa.

Cactus. Plants with fleshy stems and branches. Most have spines rather than leaves.

Cairn. A route marker. Usually a small pile of three or more stones set along a route to indicate the way to go or to mark a summit.

Canyon. Landform. A narrow chasm with steep sides cut by running water; a gorge or ravine.

Carbonate Rock. Rock. A rock composed of limestone or dolomite.

Carnivore. Animals (and a few plants) that eat other animals. Compare with Herbivore and Omnivore.

Carsonite Sign. A stiff, but flexible fiberglass route or boundary marker commonly used by land management agencies. Usually brown, the marker has space for applying stickers such as "Designated Route" or "Wilderness Area Boundary -- No Vehicles."

Cattle Guard. A cattle guard is a structure placed in a roadway that prevents cows from walking through a gap in a fence while allowing vehicles to pass through.

Cattle Tank. See Tank.

Cauline. Referring to the upper leaves on a plant or plant stem.

Cherry Stem. Legal boundary. A "cherry stem" or "cherry stemming" refers to drawing a designated wilderness area boundary around roads in such a manner as to allow the road to remain open. Cherry Stem roads often provide vehicle access to deep within wilderness areas, although technically, the road remains outside the wilderness area.

Chert. Rock. Hard, amorphous silica found in concretions and beds, often replaces other materials, often reddish or yellowish. Often used by native people to make stone tools.

Cienega. Landform. Technically a desert wetland, but I think of a cienega as more of a damp area supporting honey mesquite trees and "grassy" (sedges and rushes) areas rather than a traditional wetland with open water and ducks.

Cirque. Landform. The steep-sided head of a valley. The upper edges have the steepest slopes, and the base may be flat; usually associated with glacial erosion. The heads of many steep canyons have a similar form.

Class (as in 3rd-class or 4th-class). A difficulty rating for hiking (Class-1 through Class-4) and technical climbing (Class-5 and Class-6).

Cliff. Landform. A vertical or near-vertical rock face; sometimes not solid rock.

Community. All the plants and animals that live together in a particular place and are bound together by food webs and other interactions that are self-perpetuating. Some ecologists argue that concept of “community” implies tight and long-standing interactions among species, which may not always be the case; compare with Association.

Competition. Interactions within or among populations resulting from demand for a resource exceeding supply.

Conifer. Evergreen trees that have narrow needles (pines, firs) or scales (juniper) rather than leaves; seeds are produced in cones.

Crepuscular. Refers to animals that are active near sunset and sunrise, but not during the day or night.

Cross-bedding. A characteristic of sedimentary rocks where different layers are laid down at angles to one another; that is, not all of the layers are laid down horizontally. Cross-bedding is especially common in sandstone derived from sand dunes, but it can also form where a river flows into a lake.

Cultural Resource. Evidence of activity or occupation by native people. Generally includes petroglyphs, pottery, places of habitation, and other things or sites used by native peoples. Cultural resources are fragile and non-renewable.

Day Hike. A hike that should take no longer than one day to complete, although a long day-hike could strand a slow hiker on the trail in the dark.

Deciduous. Refers to tree and other plants that drop their leaves every year, generally during winter. Some cactus and other desert species drop their leaves during summer to conserve water.

Desert. Arid regions where evaporation rates exceed precipitation rates. In the general vernacular, areas that get less than 10 inches of rain per year.

Desert Pavement. Landform. Small stones covering the ground that creates the appearance of pavement. Desert pavement is formed by wind erosion that removes sand and soil from around the stones, leaving a surface covered only by closely packed small stones.

Desert Varnish. Black patina on the surface of rocks.

Dimorphic. Literally "two shapes." Often used to refer to species of plants and animals where the males and females look different. For example, humans are dimorphic, but many species of birds and snakes are monomorphic (look the same)

Diurnal. Refers to animals that are active during the day.

Dolomite. Rock. A metamorphic rock composed of magnesium carbonate. This rock originates as limestone, but it is metamorphosed underwater such that some of the calcium in the calcium carbonate is replaced by magnesium to form magnesium carbonate.

Dorsal, Dorsum. On an animal, refers to the back. For example, male Side-blotched Lizards get tiny blue spots on the dorsum during breeding season.

Drainage Basin. Landform. A region of land surrounded by ridges and drained by streams that eventually converge to one stream.

Drift. Mining. A drift is a horizontal mine shaft (technically an adit), that runs perpendicular to the main shaft or adit. Drifts typically do not connect to the surface.

Earthquake Fault. See Fault.

Eclipse. In reference to ducks, when males lose their breeding plumage after the breeding season in the fall, they are said to be in "eclipse plumage," In eclipse plumage, males often resemble females and may lose the ability to fly because they have lost their wing feathers.

Ecology. The study of interrelationships among plants, animals, other organisms, and the environment.

Erosion. Removal of the land surface (dirt and rocks) by wind, water, ice, landslides, and similar forces; especially removal by flowing water.

Exotic Species. Non-native species. There need be nothing particularly “exotic” about exotic species. In the Mojave Desert, exotic plant and animal species often come from southern Europe, North Africa, and the steppes of Asia. Examples are Red Brome Grass and Chukar.

False Summit. A high point on a ridge that, to tired hikers, appears to be the true summit. False summits tend to get one's hopes up, but always disappoint.

Fault. A fracture in the crust of the earth, also known as an earthquake fault. See also Thrust Fault.

Fixed Rope. A rope, often a real climbing rope, left in place by previous hikers to help others get up or down some difficult spot such as a wet, slick rock in a canyon or a slippery step-up in a cave.

Flood Plain. A low, flat area adjacent to a river that is formed by the deposition of river sediments during flooding over time. As such, these areas are subject to flooding.

Fossil. Rock. An impression or cast of an animal or plant preserved in the rock after the original organic material is transformed or removed. Animals track may also become fossilized. The remains of ancient plants and animals.

Four-Wheel Drive Road. See Road, Four-Wheel-Drive (4WD).

Glochid: Plant. On some cactus, a small (compared to main spines) barbed hair or bristle set atop an ariole; usually in dense clumps of many glochids atop each ariole.

Gneiss. Rock. A coarse-grained metamorphic rock that shows layering of minerals.

GPS (Global Position System). A set of satellites that transmit position data that can be interpreted by hand-held GPS units. Useful for route finding.

Graded Dirt Road. See Road, Graded.

Granite. Rock. A light-colored, coarse-grained crystalline igneous rock composed of quartz, feldspar, and micas. Granite forms when magma cools slowly far beneath the ground surface.

Gravel Road. See Road, Gravel.

Gully. Landform. A small, steep-sided valley or erosion channel (generally less than 30 feet across).

Guzzler. A constructed water catchment and storage device used to provide water for wildlife, usually quail or bighorn sheep. A variety of guzzlers have been built in the mountains around southern Nevada, primarily by the Nevada Division of Wildlife. See for example, the Quail Spring Guzzler in the Las Vegas Range. In the Desert National Wildlife Range, which was established to protect bighorn sheep, guzzlers primarily are for the benefit of the sheep. Elsewhere, however, guzzlers (mostly quail guzzlers) were established to benefit hunters.

Habitat. The place where things live.

Head of the Valley. Landform. In the mountains, the higher-elevation end of a valley.

Headwall. Landform. Steep slope or cliffs above gentler slopes and ending at the skyline.

Herbivore. Refers to animals that eat plants. Compare with Carnivore and Omnivore.

Hiking. implies Class 1 or Class 2 skills (generally not needing hands for stability) to travel over the landscape.

Hoodoo. Landform. A thin spire of rock made of soft, erodible rock, but topped with a harder rock that protects the top from erosion. Hoodoos typically have an irregular shape.

Hot Spring. Landform. A place where hot water naturally emerges from the earth.

Igneous Rock. Rock. Volcanic rock.

Involucre. Plants. A series of bracts beneath or around a flower or flower cluster; a group of phyllaries (e.g., the ball of spines at the base of a thistle flower).

Lava Tube. Landform. A tunnel formed when the surface of a lava flow cools and solidifies, but the molten material under the surface remains fluid and drains away, leaving behind cavities or tubes.

Lichen. Colorful, plant-like organisms that grow on rocks and other surfaces. Lichens are a symbiotic association between an algal species and a fungal species that grow together as a single organism.

Limestone. Rock. A sedimentary rock composed of calcium carbonate, usually as the mineral calcite.

Lollipop Loop Trail. A trail in the shape of a lollipop: a stick with a bulbous end. A type of trail where hikers start on a trail that eventually forks to make a loop that comes back to the fork. Hikers then return to the trailhead over the same trail on which they started. See, for example, Pine Creek Loop Trail and Two Springs Loop Trail.

Lowland. Landform. Generally flat land at an elevation lower than the surrounding area.

Meadow. An open grassland in a forest or other habitat type.

Mesa. Landform. A steep sided, flat-topped hill formed by erosion of the surrounding materials. Mesas are often capped by a resistant rock layer (e.g., basalt) that protects softer underlying rocks. Mesas are wider than tall; compare with butte.

Midden. Generally, an old trash pile. In reference to native peoples and early settlers, middens are an important source of information on what these people ate, wore for clothing, and used for tools. In reference to woodrats (packrats), middens are an accumulation of plant material, other materials, urine, and feces found in caves and other sheltered places that are important for understanding historical changes in climate (see the Cave Canyon hike for more information).

Migration. Annual movement of animals from one region to another in search for better climatic conditions; a common habit for waterfowl and many other bird species, some large mammals, bats, and fish.

Monomorphic. Literally "one shape." Often used to refer to species of plants and animals where the males and females look the same (at least to us humans, they certainly can tell each other apart). For example, many species of snakes are monomorphic, but humans are dimorphic.

Moraine. Landform. An unsorted mix of boulders, rocks, gravel, and sand ground out and pushed ahead of (or along side) a glacier. Around Las Vegas, look for a moraine on the way to Big Falls on Mt. Charleston.

Mountain. Landform. A large, high land mass that projects above the surrounding area.

Multiple-trailing. Trails. Refers to a situation where hikers walk off the main trail and develop two or more adjacent trails where there should only be one trail. Multiple trailing is a symptom of lazy people, poor trail design, or poor land management, and results in money wasted on trail maintenance that should not be necessary.

Narrows. Landform. A narrow place in a canyon characterized by vertical walls and often only a few yards across.

Nocturnal. Refers to animals that are active at night.

NPS (United States National Park Service). A branch of the federal government charged with managing public lands, primarily National Parks and National Recreation Areas. Around Las Vegas, the NPS manages Zion and Death Valley National Parks, Lake Mead National Recreation Area, and Mojave National Preserve.

Obsidian. Rock. Volcanic rock that cools very quickly and forms glass. Usually black. Used by native peoples to make arrowheads and other cutting tools.

Omnivore. Refers to animals that eat plants and animals. Compare with Carnivore and Herbivore.

Paiute. One of the groups of native peoples who inhabited southern Nevada for thousands of years before settlement by European people.

Panicle. A branched cluster of flowers in which the branches are racemes, where a raceme is a stalk of flowers arranged singly along a stem.

Parasite. An organism that feeds on or in other host organisms while contributing nothing to the survival of the host.

Parotid Gland. On a toad, a small, round or oval, raised gland behind and above the eye; much larger than the warts.

Peak. Landform. The highest point on a mountain. See Summit.

Perennial Plant. Refers to plants that persist from year to year. Compare with Annual.

Petroglyph. Rock Stories -- Etchings made on rocks by native people hundreds or thousands of years ago. Petroglyphs are carved into the surface of rocks, usually by removing the surface coating of desert varnish to reveal the color of the underlying rock.

Pictograph. Rock Stories -- Paintings on rocks made by native people hundreds or thousands of years ago. Pictographs are painted into the surface of rocks using plant and mineral pigments.

Playa. Landform. A normally dry lakebed, usually white in color from the salts and clay materials that form the surface; often surrounded by salty soils.

Pluton. Landform. A mass of volcanic rock that pushes towards the surface of the earth, but does not break through, and cools slowly underground. The result often is a coarse-grained granitic rock.

Potable Water. Drinkable water (tastes OK, no pollutants, no harmful chemicals).

Pothole. Landform. A rounded hole in the bedrock of a stream bed, formed by the abrasion of small, water-borne pebbles in the current. See also Tank.

Pour-over. Landform. A usually dry waterfall. A place in a wash or canyon where water, if it were flowing, would “pour over” a ledge to form a waterfall. Also called a dryfall. Compare with “waterfall,” a normally wet waterfall.

Pyroclastic Rock. Rock. A rock formed by the accumulation of fragments of volcanic rock scattered by volcanic explosions.

Quartzite. Rock. A very hard, white metamorphic rock formed from quartz sandstone (metamorphic sandstone).

Rain Shadow. Landform. As moist air pushes up over a mountain range, the air cools, the moisture condenses into clouds, and it may rain. As the air passes over the mountain range and descends the other side, the air warms and dries, reducing the chance of rain on the downhill side. The area where it doesn't rain is the rain shadow.

Rachis. Plant, Bird. An axial structure such as the central stem of a feather or the main and side stems of an inflorescence (flowerhead).

Rock Stories. Rather than use the term "rock art," which some Native Americans feel is pejorative, I'm trying to use the phrase "rock stories." The descendants of the Ancients say that petroglyphs and pictographs are equivalent to written text, and to treat them as less than text (i.e., artwork), denigrates the meaning of the symbols and insults the writer.

Ridge. Landform. A long narrow upper section or crest; a long narrow chain of hills or mountains. An area of high ground separating two canyons formed by erosion on both sides. Ridges range in size from those between small gullies to the crest of an entire mountain range. Also called ridgeline.

Rill. A backroad feature where storm waters flow across a road and leave a deep, narrow, steep-sided ditch (the rill) rather than the more normal washed-out dip in the road.

Riparian. Landform. Refers to wet areas in the desert with shrubs and trees. Desert canyons with streams, such as Grapevine Canyon, often have "riparian areas," and the Overton Wildlife Management Area and parts of the Pahranagat Valley are riparian.

Road, Four-Wheel-Drive (4WD). An unmaintained roadway that might require driving over and around boulders, driving in deep, soft sand or deep gravel, driving up steep, loose hillsides, and driving in similar situations where large rocks or soft substrates require traction and power to all four wheels. It only takes one such spot to make an otherwise ordinary road into a 4WD road.

Road, Graded. A maintained, but unsurfaced dirt road that is graded on some regular schedule or after rainstorms. Graded roads generally are suitable for sedans, but they can be rocky, muddy, or washed out.

Road, Gravel. A maintained road that is surfaced with gravel rather than pavement. Gravel roads generally are suitable for sedans, but they can be muddy or washed out.

Road, Two-Track. A roadway recognized only by tire tracks running out among the bushes and rocks. Two-track roads are not graded, although they may have been long ago, and they generally require a high-clearance vehicle to avoid the bushes and rocks on the hump between the tire tracks. A two-track is a real road with a long history of use, not just the tracks of some illegal off-road driver.

Route. A way to go, but not a trail or use-trail. Cairns may mark a route, or a route might run up a wash or across slickrock.

Saddle. Landform. A low point on a ridge; a pass. Saddles on a ridgeline generally are broad with gently sloping sides, like a saddle on a horse. This is in contrast to a steep sided “notch” on a ridgeline.

Sandstone. Rock. A sedimentary rock composed of sand grains cemented together by other minerals.

Scat. A general term that can be applied to the droppings of any animal, but usually applied to elongate droppings from mammals such as coyotes, foxes, bobcat, and weasels. Rabbits, deer, and bighorn sheep have pellets, and small rodents such as field mice and kangaroo rats just have droppings. Packrats also have droppings, which accumulate to form middens (see Midden).

Schist. Rock. A metamorphic rock characterized by strong foliation.

Scrambling. Implies Class 3, Class 4, or minimal Class 5 climbing skills (generally needing hands for stability, but not ropes for safety) to travel over the landscape.

Scree. Landform. The small, loose stones (sometimes gravel) that cover a slope.

Sedimentary Rock. Rock. Rock formed by the accumulation and materials transported by wind, water, or ice to the site of deposition (e.g., sandstone or mudstone). Also chemically precipitated materials (e.g., limestone).

Sexual Dimorphism. Refers to the case where males and females of a species look different. For example, male fence lizards have blue bellies and throats, while females do not; in many species of birds, the males are more colorful than females.

Shaft. Mining. A vertical or near vertical mine opening. In mines, there are vertical shafts, horizontal adits, and various angled inclines and ramps.

Shard. Piece of broken pottery. Usually used in the context of Native American artifacts (as in "pot shard"). Could be used to refer to stone flanks left behind after making a stone tool (e.g., arrowhead or scraper).

Shinarump Conglomerate. Geology. The Shinarump Conglomerate is the lowermost member of the Chinle Formation and is about 225 million years old (middle Triassic). It has red jasper clasts (pebbles) and is overlain in places by a sandstone containing petrified wood (still part of the Shinarump Conglomerate Member). The rock layer forming the First Creek Falls are Shinarump Conglomerate. Compare with Timpoweap Conglomerate.

Shrub. A woody perennial plant, usually with multiple trunks or stems and growing to less than 8-feet tall.

Slickrock. Landform. A broad expanse of fairly smooth rock; often associated with sandstone.

Strata; Stratification. Landform. The structure of sedimentary rocks where parallel beds of considerable lateral extent can be seen. See bedding.

Spp. Abbreviation for species (usually plural). Used in the context of a genus name followed by "spp." (e.g., Scirpus spp.) and refers to any unidentified species in the genus Scirpus. For example, a number of species of Sedge (Scirpus spp.) occur in Nevada, and most are too hard for me to identify to species.

Subtree. A woody perennial plant, usually with multiple trunks or stems and growing to about 8-feet tall. A tall shrub generally taller than typical shrubs, but not quite a tree.

Summit. Landform. Usually the highest point on a mountain, but also the highest point on a hill or other elevated point.

Switchback. In steep terrain, trails often zigzag up the hillside. The point where the trail turns nearly 180 degrees to go back across the hillside is a switchback. Such a trail is said to switchback up a hillside.

Syncline. Landform. Layers of rocks bowed down in the middle to create a trough. See also Anticline.

T-post Sign. A metal fence post, T-shaped in cross-section and usually used for barbed wire fences, used as a route or boundary marker. Usually green, the post has bumps on one side to facilitate holding things in place (e.g., signs) when wired to the post.

Talus. Landform. A deposit of large broken fragments of rock, usually at the base of a cliff or on steep slopes.

Tank. A depression in the rocks, usually in some elevated place, that holds water, but not in a streambed (compare with Pothole). Early cattlemen built many small dams across narrow gorges to capture rainwater, and they referred to these as “cattle tanks” or simply “tanks.” The dams usually were constructed in vertical sections by pouring concrete between wooden frames, letting the cement harden, then moving the frames up to pour the next layer. See also Pothole. Natural tanks often are called potholes, but man-made tanks are always called tanks.

Tectonic. Geology. Refers to the forces within the earth that move continental plates and the earthquakes and mountain building that result.

Thrust Fault. Geology. A type of earthquake fault where the land surface is compressed, and the land on one side of fault is forced up and over the land on the other side of the fault. See also Wikipedia.

Timberline. The maximum elevation at which trees can survive -- the end of the trees -- because the cold and wind are too severe for trees to survive. Around Las Vegas, timberline forms the boundary between the Bristlecone Pine Forest and the Alpine life zones at about 11,500 feet elevation.

Timpoweap Conglomerate. Geology. The Timpoweap Conglomerate is the lowermost member of the Moenkopi Formation and is about 250 million years old (lowermost Triassic). The Timpoweap is composed mostly of limestone clasts (stone fragments), and at its base has big chunks of the underlying limestone in a basal breccia. The Muffins, atop Blue Diamond Hill, are comprised of Timpoweap Conglomerate. This is equivalent to the Rock Canyon Formation in Utah. Compare with Shinarump Conglomerate.

Tinaja. Landform. Usually a depression in bedrock that collects rainwater and snow melt. Similar to a Pothole, but not always associated with water courses. See also Tank.

Trail. A path laid out, developed, and maintained by a land management agency such as the U.S. Forest Service. Trails usually have signs, a wide tread, switchbacks, and waterbars to direct water off the tread. See also Use-Trail and Route.

Trailhead. The place where the driving ends and the trail begins.

Tread. The part of a trail or use-trail that you walk on.

Tree. A woody perennial plant, usually with a single trunk or stem and growing eight or more feet tall.

Tuff. Rock. A volcanic rock composed of pyroclastic fragments, fine ash, or both. The particles may be melted slightly by the volcanic heat to produce a welded tuff.

Two-Track Road. See Road, Two-Track.

Unconformity. Landform. The line between layered strata of different ages representing an interval of time in which deposition stopped, erosion removed some material, and then deposition resumed. A period of time missing from the geologic record.

Use-Trail. An unofficial trail pounded into the ground by the passage of hikers. Use-trails almost never have signs, the tread usually is narrow, and they tend to go steeply up and down hillsides.

USFS (United States Forest Service). A branch of the federal government charged with managing wild forested lands. Historically, the USFS focused on leasing lands for logging, mining, and other extractive uses, but recently it has become more friendly towards the environment and now manages recreational areas such as the Spring Mountains National Recreation Area (SMNRA) and several Wilderness Areas in southern Nevada.

USFWS (United State Fish and Wildlife Service). A branch of the federal government charged with managing wildlife. The USFWS is best known for managing the recovery of endangered species such as the desert tortoise and several species of desert fishes. The USFWS also manages the Desert National Wildlife Range and the Moapa and Ash Meadows National Wildlife Refuges in southern Nevada.

Ventral. On an animal, refers to the belly. For example, male Spiny Lizards and other “blue-belly lizards” have blue patches on the ventral surface.

Volcanic Ash. Rock. Fine volcanic dust formed when gases escaping from a volcano force a fine spray of magma into the air.

Volcanic Breccia. Rock. Pyroclastic rock in which all fragments are more than 2 millimeters in diameter.

Volcano. Landform. Any opening through the crust of the earth that allows magma to reach the surface, including the deposits immediately surrounding the opening.

Wash. Landform. An intermittent streambed where water may flow after a rain.

Waterbar. A water diversion device used on constructed trails to divert water off the trail and prevent erosion.

Waterfall. Landform. A place where a perennial stream or river falls or cascades over a cliff. I'm trying to restrict the use of this term to perennial streams. Compare with "pour-over," which I'm trying to use for normally dry "waterfalls."

Waypoint. GPS coordinates for a place. Waypoints (Wpt.) can be recorded on the trail with a hand-help GPS unit, read from a map, or downloaded from the Internet.

Weathering. The physical or chemical decomposition of rock due to exposure to atmospheric elements; contrast with erosion.

Wilderness. Undeveloped and uncultivated land that generally still is in pre-settlement conditions. In a legal sense, lands protected by from development by federal law.

Winze. Mining. A vertical "shaft" connecting one horizontal level inside a mine with another horizontal level inside the mine.

Wpt. Abbreviation for "Waypoint." A GPS coordinate for a place.