Susan Tweit

Susan J. Tweit is a scientist who evolved into an award-winning writer and radio commentator. She is the author of five books for adults, including Barren, Wild, & Worthless: Living in the Chihuahuan Desert, personal stories about the history and natural history of Southern New Mexico, The Great Southwest Nature Factbook, a browser's guide to nature in the Southwest, from A to Z, and Seasons in the Desert: A Naturalist's Notebook, from Chronicle books. She has also written two children's books, Meet the Wild Southwest: Land of Hoodoos & Gila Monsters (Alaska Northwest Books) and City Foxes, a picture book which was named one of the Outstanding Science Books for Children for 1998.

Her "Wild Lives" radio commentaries are heard three times weekly on KRWG-FM, Southern New Mexico public radio, and her columns run in the Las Cruces Sun News. Susan's essays and stories have appeared in Harrowsmith Country Life, New Mexico, Sierra, Cricket, Bloomsbury Review, and other magazines. She is the co-founder of Las Cruces' wildly popular - and fun - Border Book Festival. She is currently living in Colorado with her husband, Richard Cabe, and dog, Perdida Imelda.

Susan is a popular public speaker and leader of workshops. Her stories of our natural and human history have captivated a wide variety of audiences, including school classes, workshops, banquets, and professional meetings. As Bloomsbury Review put it, she brings the precision of a scientist and the passion of a poet, and is able to refocus readers' vision and ignite their imaginations.

Look for Susan's forthcoming book, Seasons on the Pacific Coast, due out from Chronicle Books in 1999. She is currently writing a memoir, Navigating by the Stars.

Susan has a new web site! She invites you to come visit. Her books are available there, at local bookstores, or on-line through http://BarnesandNoble.com and http://Amazon.com (search by author for Susan Tweit).

Published on 01/11/2003

On these hot, dry June days when the horizon shimmers, set to dancing by the waves of heat that rise from the ground, I think of beaches. Not ocean beaches - playas -desert beaches. Playas are the dry, incredibly level beds of ancient lakes. Found in desert country throughout the southern Southwest and northern Mexico, and the Great Basin country of western Utah and Nevada, normally-dry playas occasionally fill with a skim of water - sometimes no more than inches deep over many square miles - after a heavy summer rain or spring snowmelt. Such lakes never last more than days or weeks, soon evaporating to leave behind huge expanses of mudflats drying in the sun. Playas were named by Spanish explorers for their resemblance to beaches - very flat beaches.

Playas

On these hot, dry June days when the horizon shimmers, set to dancing by the waves of heat that rise from the ground, I think of beaches. Not ocean beaches - playas -desert beaches. Playas are the dry, incredibly level beds of ancient lakes. Found in desert country throughout the southern Southwest and northern Mexico, and the Great Basin country of western Utah and Nevada, normally-dry playas occasionally fill with a skim of water - sometimes no more than inches deep over many square miles - after a heavy summer rain or spring snowmelt. Such lakes never last more than days or weeks, soon evaporating to leave behind huge expanses of mudflats drying in the sun. Playas were named by Spanish explorers for their resemblance to beaches - very flat beaches.

Playas are characteristic desert landforms, maintained by climates drier than they are wet, where the combination of relentless sun, wind, and thirsty air can evaporate many more times moisture from the land than falls on it in a year. Most of the Southwest's playas formed during our last extended rainy season, many thousands of years ago. During the Pleistocene, the glacial era in the Northern Hemisphere, the climate in the Southwest was cooler and much wetter. With more precipitation, streams and rivers abounded. Yearround streams rushed down now-dry drainages in the mountains, eroding boulders, cobbles, gravel, sand, and silt as they ran, dropping the larger, heavier sediments where the water slowed down at the edge of the mountains. The basins between mountain ranges filled up with finer sands and silts, atop which floated shallow lakes.

As the climate warmed and dried some ten to twelve thousand years ago, the streams dried up and the basin-filling lakes evaporated, leaving their flat-floored beds to dry and harden to a cementlike consistency. The beds of these long-vanished lakes, including the Lordsburg playa and Lake Lucero, the playa that supplies gypsum sand for White Sands, are today's desert playas.

When the lakes return briefly, the profusion of salty water teems with tiny aquatic lives: algae, freshwater shrimp, brine flies. These suddenly appearing residents survive the intervening months or years of drought as eggs or encysted larvae in the cracks of the dry playa, waiting for water's next blessing.

When the water evaporates, it leaves acres of shiny, gooey mud flats, level as the surface of a pool table, encrusted with a new coat of calcium, sodium, gypsum, and other salts from the recently-departed water. The mud surface dries into curls, pie-wedge-shapes, cylinders, or shardlike plates. Polished by the ever-constant wind, it sometimes shines like glass. The flat expanses are exhilarating, Ann Zwinger says in The Mysterious Lands, "I stand, like the pivot point of a compass, in the center of the universe-a place to dance, to hoot and holler, the rearrange mountains, to count the rollicking stars at night."