Fossil dunes, monsoon deserts, By Tim Hazell, Oct 6, 2006

My real gift was the song, that gentle lullaby,

Burnt with your lips til you set it free,

An impoverished shape, dissonant and limping

That jangled into the red desert.

I am left trying to remember the rituals of singing without fear.

Heating up on the equatorial sides of the Horse Latitudes, trade winds move in two belts toward the equator. Dry currents dissipate cloud cover, allowing the sun to bear down on arid lands. Trade wind deserts follow the path of their namesake winds, including North Africa’s Sahara, the world’s largest sea of sand. These desiccated universes have waxed and waned since the beginning of the agricultural revolution, frequently encroaching upon human settlements and farmlands. Fossil sediments from ancient beds of sand as much as 500 million years old are found throughout the world, including in rainforest environments. Dominant weather patterns and geographical locations determine the characteristics of deserts as trade wind, rain shadow, coastal—such as Peru’s Atacama—or polar. The Arctic tundra represents a vast area of desertification in Canada’s far north, while inland Antarctic dry valleys have been snow-free for thousands of years.

Desert siroccos that blow in one direction shape a wilderness of articulating dunes, some with crest-to-crest widths of more than three kilometers. These leviathans remain poised, expectant, until build-ups of sand at the brink exceeds their angles of repose, causing small avalanches to slide down the slipfaces, or leeward sides. Then slowly, majestically, grain by grain, the dunes are on the march—downwind, crossing the sun’s anvil, their undulations bathed in light and shadow. Here are places in transition, like fragile webs, a delicate balance where equipoise is precarious, a cantilevered arrangement of microclimates.

In these marginal areas, human activities stress the ecosystem beyond its tolerance limits, resulting in degradation of the land. Grazing livestock compact the substrate with their hooves. The collection of firewood eliminates plants that help to anchor the soil. For the inhabitants of the Sudan, moisture symbolizes life itself, particularly in the dry season when deep wells must be dug to reach the water table. The Mesakin Nuba, one of many tribes throughout the region, are an agrarian people whose quality of life hinges on abundant yields of staples, particularly “dura,” their word for “sorghum.” Clay-based soils fire in temperatures that exceed 100 degrees Fahrenheit during the dry season. Beds for growing crops must be broken up by hand, using primitive shovels.

“Monsoon” is Arabic in origin, the word for “season.” Wind systems are prone to seasonal reversals, the spawn of temperature variations between continents and oceans. Traders’ southeastern winds of the Indian Ocean produce a summer deluge as they move onshore, crossing the Indian continent before losing moisture on the slopes of the Aravalli Range. Monsoon deserts, such as the Rajasthan of India and the Thar Desert of Pakistan, spread where dry regions are born west of the range.

Zephyrs near the Earth’s surface scatter the granules aloft as dust or haze. Parched atmospheres are crowded with fragments in suspension, held indefinitely in the biosphere by upward currents of air that support their weight. Saltation moves small particles in the direction of the wind in a series of short hops or skips. A saltating grain may hit other grains that jump up to continue the process. Eolian turbidity currents produce dust storms. Rain passes through and cools the desert. This sinks, chilled and dense, toward the surface and reaches hot ground, deflecting air forward. Turbulence sweeps up surface debris in its wake as a dust storm. Compact winds—dust devils—whirl like dervishes over arid land, related to intense local heating and destabilization of the air mass. These can create gyrating funnels a kilometer in height.

On occasion, sand seas are wracked by violent storms. When a rare shower is imminent, the water can torrent. Dry stream beds, called “arroyos” or “wadis,” quickly fill, making human crossings dangerous. Regal waters such as the Nile flow through hostile environments, their volumes derived from rain and snow accumulations from highlands at their origins. Sediments are picked up and deposited as these courtesans meander their way to the sea. Civilizations based on alluvial residues spring up and flower as ripples in their wake.

Desert plants are tolerant of drought and the salt content from small reservoirs of concentrated water that they store in leaves, roots and stems. In Mexico’s semi-arid central plateau regions, plant cover is typically lean, but of great diversity—as is the animal life that benefits from aquifers and springs. Cacti, deciduous trees and aquatic plants thrive, some reintroduced through conservation. Fauna include species of birds, reptiles and mammals adapted to meager habitats. Reservoirs often support verdant shoreline growth, fish and varieties of birds. The dry chaparral represents a Mexican highland panorama of grasses, mesquite and huizache trees and the stately garambullo or candelabrum cactus. Summer rains turn these regions into palettes of greens interspersed with riots of multicolored blooms.

For the inhabitants of deserts and regions with water shortages, quarrels over allocations in newly appropriated ecozones readily mushroom into structural conflicts between ethnic lines of demarcation. Equilibrium in vast tracts of the world’s arid and semidesert areas is dependent upon environmental harmony and balanced equations of soils, climates, water, flora and fauna. Modern conditions such as global warming exacerbate persistent drought. Widespread famine results. In the process of readapting to variant ecological habitats, environmental borders are created. Unfortunately for the millions of homeless and dispossessed, these often become ethnic and cultural identification criteria. Fragile ecology means fragile peace.

Tim Hazell is a multidisciplinary artist in the areas of painting, music, theater, education, writing and research, specializing in Latin America. He may be contacted at hazel@unisono.net.mx or at his website, www.timhazell.com