The Great Sand Sea is a vast body of erg (sandy) desert
stretching about 480 miles (772 kilometers) north to south
from Siwa Oasis to Gilf Kebir, and 120 miles (193 kilometers)
west to east from the Libyan border to Farafra Oasis. It consists
mainly of almost lifeless sand dunes. People rarely set foot on
this desert wilderness, and it has long been a barrier to trade
and movement. The Greek geographer and historian Herodo-
tus claimed that 50,000 Persian soldiers died trying to cross it
when a ferocious sandstorm overtook them.
Embedded in the Western Desert’s limestone plateau
are several great oases depressions, the main locations of life
in the Western Desert. Their formation began during ancient
periods of abundant rainfall, when water widened fractures
in the plateau floor. Winds then carved some of these fissures
deeper and deeper, finally cutting into water-bearing levels in
the limestone rock. This process created the principal oases
and depressions of the Western Desert: Wadi el Natrun, Siwa
Oasis, Qattara Depression, Bahariya Oasis, Farafra Oasis, and
Dakhla Oasis. The typical Western Desert depression is nearly
or completely encircled by steep cliffs, or escarpments. Its
floor is near or below sea level. There are some good soils, and
where water breaks the surface as springs there is a productive
irrigated agriculture. In poorly drained low-lying areas of the
depression floors, excess water accumulates in salty lakes sur-
rounded by salt marshes, making it impossible to farm. Aside
stretching about 480 miles (772 kilometers) north to south
from Siwa Oasis to Gilf Kebir, and 120 miles (193 kilometers)
west to east from the Libyan border to Farafra Oasis. It consists
mainly of almost lifeless sand dunes. People rarely set foot on
this desert wilderness, and it has long been a barrier to trade
and movement. The Greek geographer and historian Herodo-
tus claimed that 50,000 Persian soldiers died trying to cross it
when a ferocious sandstorm overtook them.
Embedded in the Western Desert’s limestone plateau
are several great oases depressions, the main locations of life
in the Western Desert. Their formation began during ancient
periods of abundant rainfall, when water widened fractures
in the plateau floor. Winds then carved some of these fissures
deeper and deeper, finally cutting into water-bearing levels in
the limestone rock. This process created the principal oases
and depressions of the Western Desert: Wadi el Natrun, Siwa
Oasis, Qattara Depression, Bahariya Oasis, Farafra Oasis, and
Dakhla Oasis. The typical Western Desert depression is nearly
or completely encircled by steep cliffs, or escarpments. Its
floor is near or below sea level. There are some good soils, and
where water breaks the surface as springs there is a productive
irrigated agriculture. In poorly drained low-lying areas of the
depression floors, excess water accumulates in salty lakes sur-
rounded by salt marshes, making it impossible to farm. Aside
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