For anyone who has ever been in a desert you know how desolate, lonely, and isolated the landscape can be. Life without reliable water sources coupled with the constant need to travel many days between the next water sources have been a theme of trade, travel and nomadic lifestyles for centuries. Life in harsh climates is hard to maintain for many creatures on Earth, including humans, and yet thousands of plant and animals species have managed to thrive in these harsh environments quite well. Oases are interesting and vital parts of an ecosystem that can be found all around the world; along with being a unique geographical feature they provide water, shelter and shade for people passing through as well as plants and animals that live in the area of the oasis.
How an Oasis Develops
Each and every oasis is different and can be created because of a few factors. Oases can be naturally formed or man-made and their water sources can spring from a few places. An oasis can be formed by an underground aquifer or river that creates enough pressure for water to seep to the surface, forming the oasis. These aquifers and natural springs allow for life to exist in harsh climates like the desert and are often well known to local herders, farmers, and travelers in the region. Water in the oases can come from underground or from above-ground forces like rainstorms, surface rivers and the natural environment of the oasis protecting the oasis zone. Above ground rivers can help form underground aquifers that create oases far away from the river itself, proving the extraordinary nature of oases as a geographical feature.
Certain other geological factors also influence how an oasis gets its water. Rock layers under the surface of the Earth help trap and channel water in pockets and along fault lines, leading to water seeping into an oasis via the surface or into a nearby aquifer. Certain kinds of rock are suited for water retention or passage and can help facilitate the creation and maintenance of an oasis in the desert. In some cases where an aquifer might not have enough pressure to break through to the surface, a man-made well would be build as the catalyst for drawing water to the surface. This ensures the survival of an oasis and can help jump start a natural spring that continues to feed an oasis long into the future.
Oases are maintained by nature and by men. Some man-made wells near oases in parts of the world have been maintained for generations in order to keep the oasis as a viable water source for travelers, livestock and communities nearby that rely on the water for survival. The natural environment of the oasis also lends itself to water preservation and conservation; the trees, shrubs and other flora that thrive in the environment of the oasis help retain water in the ground and shade the oasis from the elements around it. Oases located in the desert (as most are) are constantly threatened by shifting sands and other weather-related factors and are protected by the shelter of trees around it. Palm trees, tubers, and other plants are especially good at protecting an oasis from harmful elements and contribute greatly to the environment of the ecosystem because of their deep roots and exceptional water retention abilities.
Oases that are fed by above-ground rivers, like the Nile River, can be created by underground aquifers and rock layers thousands of miles away. This vital relationship between oases and rivers mean that water sources can be maintained and created even with no water sources visible nearby. Other geological features like lakes, streams and oceans can also be sources of water in an oasis depending on the location.
An oasis is a vital part of life in the desert as well as other harsh and dry climates around the world. Without oases travel and trade routes would have been made nearly impossible, and the feeding and watering of people and livestock would be made nearly impossible. We can’t all live directly by a body of fresh water, but oases help maintain and sustain life in the harsh interior of continents around the world.
References
Wikipedia. Oasis. Web November 2014. https://en.wikipedia.org/wiki/Oasis
National Geographic. Education. Encyclopedia: Oasis. November 2014. Web November 2014. http://education.nationalgeographic.com/education/encyclopedia/oasis/?ar_a=1
