Love ’em or leave ’em, the deserts of the U.S. are not only interesting, important for the health and survival of the planet, but are also incredibly beautiful! There are a number of different types of deserts in the U.S., and if you are in the area of one (especially in Regions 7 & 9), you just might get more out of what you are seeing if you have a few fun facts and some interesting information.
DEFINITION: According to Merriam-Webster, the definition of a ‘desert’ is:
“1a : arid land with usually sparse vegetation; especially : such land having a very warm climate and receiving less than 25 centimeters (10 inches) of sporadic rainfall annually b : an area of water apparently devoid of life. 2 archaic: a wild uninhabited and uncultivated tract.”
BASIC CHARACTERISTICS OF A DESERT:
People often use the words “hot,” “dry,” or “empty” to describe deserts, but these words do not tell the whole story! Most deserts, far from being empty and lifeless, are home to a variety of plants and animals, and are important to the sustainability of the earth. Here are a few facts that are true of all desert types:
*Desert is a type of ‘Biome’, (which is defined as: ’A large community of plants and animals that occupies a distinct region’). *Deserts cover about 20% of the Earth’s surface
*Deserts get less than 10” of rainfall each year.
*Desert biomes can be found on every continent except Europe.
*A desert has little to no surface water and high evaporation. Because there is no humidity, there is no protective layer regulating the temperature or filtering the sun’s rays. As a result, a desert is hot during the day and cold at night.
*Most of the animals that live in the desert are nocturnal so they are up and feeding at night when it is cooler. Most also live in the ground to protect them from the heat and they store water in their bodies.
*Due to the lack of moisture in the desert, the wind grinds pebbles and sand into dust. When a heavy wind comes up it can create a dust storm. Dust storms can reach over 1 mile high and can travel thousands of miles.
*Deserts all over the world are expanding, some growing by 30 miles each year.
*The soil in the desert needs only water and is therefore nutrient rich.
*Many animals and birds use the desert as a migration path and as a stopover for food.
*Deserts are the primary source of table salt, borates, potassium, sodium nitrates and gypsum. Soda, nitrates and boron are evaporite minerals that appear only in deserts. Approximately half of the world’s stores of fossil fuels come from deserts, including oil and natural gas, and nearly half of the world’s diamonds, copper, gold, bauxite, iron ore and uranium ore.
SOME OF THE MORE COMMON LANDSCAPE FEATURES OF A DESERT:
–Sand Dunes: Sand Dunes are a beautiful and mysterious natural wonder. Over many years dunes are formed where there is a source of dry sand, a means to transport sand and a sheltered place for the sand to rest and get trapped. The wind constantly changes the size and shape of a dune, and the dunes act as a barrier protecting the landscape around it. Sand Dunes can be freshwater or coastal.
-Desert Pavements: Desert pavements are large areas of the desert floor that is covered with interlocking, angular pebbles, stones and gravel that are too heavy to be blown away by the wind.
-Playas: A Playa is a dry, flat, vegetation-free area located at the lowest part of a desert basin. During wet periods, these basins fill with water.
-Oases: Oases is plural for Oasis which is a pond or small lake located near a water source that can support vegetation.
-Mesas: A Mesa is a large hill with a flat top and steep sides. It is formed by erosion when water washes the softer parts of the hill away leaving the solid rock center. A Mesa is wider than it is tall and is found in dry areas where the rock layers are horizontal.
-Buttes: A Butte is similar to a Mesa and is formed basically the same way. The difference is that a Butte is taller than it is wide and is smaller than a Mesa.
-Alluvial Fans: An alluvial fan is a fan- or cone-shaped feature in the landscape where silt, sand and gravel have been deposited by sudden and harsh flash flooding through narrow gaps in hills and canyon walls. Fans can spread over an area as much as 50’.
SOME COMMON TYPES OF DESERTS:
1). Hot and Dry Deserts
*The three major North American deserts that are Hot & Dry are the Chihuahuan (TX), the Sonoran (AZ), and the Mojave (CA). (Temperatures in the Hot & Dry desert are extremely hot in the summer and warm the rest of the year).
*There is little to no rainfall in the Hot & Dry desert during the summer months.
*Soils are course-textured, shallow, rocky or gravely with good drainage and have no subsurface water. They are coarse due to less erosion by water. The finer, smaller sand particles are blown away by the wind, leaving heavier pieces behind.
*Generally speaking, Hot & Dry deserts have no canopy or moisture in the air, so plants are mainly short shrubs that hug the ground, trees that are short and woody and cacti that can hold their own moisture.
*Animals that live in the Hot & Dry desert have special adaptation skills that allow them to survive. Many stay dormant underground for long periods of time and become active and breed only when the rain falls. Most are carnivores due to the lack of vegetation.
*The Hot and Dry desert provides the earth with sand and oil.
*Many Hot & Dry deserts contain Hoodoos which are sandstone or volcanic rock spires that resemble totem poles or piles of flat rocks stacked on top of one another.
2). Semiarid Deserts
*Semiarid deserts see temperatures in the summer only as high as 100°during the day and 50° at night.
*Semiarid deserts are usually found at lower elevations and in the Northern Hemisphere.
*Soil in the Semiarid desert is fine and sandy.
*Plants in this type of desert have shallow roots and are easily pulled out. To protect themselves, they have painful spikes and taste bad.
*There are many more mammals, small birds, reptiles, and insects here than in the Hot & Dry desert.
3). Coastal Deserts
*Coastal deserts are complex because they exist where land, ocean, and atmospheric systems all mix.
*Coastal Deserts are found along the coasts of South America (Chile) and Australia. There are no coastal deserts in the U.S.
*Cold Deserts are found at higher elevations and are separated from the coast by remoteness or mountain ranges acting as barriers.
*The temperatures in a Cold Desert can get below 0°.
*It snows in a cold desert and has long winters and short, cool summers.
*The soil of a Cold Desert is heavy, dense and porous in order to hold all the moisture possible. The soil is also heavy with silt and salt.
*There are few plants that survive here, but there are many forms of moss and fungi.
*Most of the mammals that live in a Cold Forest are able to hibernate or live underground.
*Winds are high here as in any desert, and sandstorms often come in the form of blizzards.
**Nevada’s Great Basin Desert ranks #9 of the world’s largest deserts covering 200,000 square miles. (The Sahara Desert in Africa is #1 covering over 300 million square miles). It is the only Cold Desert in the U.S.
**The Great Basin is a warmer type of Cold Desert than many of the others and is home to a few species of plants and animals. It also features Bristlecone Pines (trees that hold the record for the oldest living organisms on the planet) that are as old as 5,000 yrs.
**The Great Basin Desert only exists because the Sierra Nevada and Cascade Mountains create a ‘rain shadow’. This cools the Pacific Ocean air and strips it of its moisture. The air in the mountains becomes dry enough to absorb moisture from the region causing the desert conditions.
Deserts in the U.S. can be found primarily in Regions 7 and 9
So next time you get a hankerin’ to see the desert southwest, take along a little info!!