Bani Yas Island is located in the Persian Gulf near the western
coastline of the United Arab Emirates (UAE). Roughly 14 kilometers (9.7
miles) by 9 kilometers (6 miles), the island is the surface expression
of a salt dome, which is a pocket of salt minerals that balloons upward into overlying layers of sedimentary rocks.
Salt domes start during past periods of alternating wet and dry
climate. A common scenario is an enclosed basin that is alternately
flooded and then subjected to extreme drying. High rates of evaporation
deposit thick layers of salt minerals, such as common table salt and
gypsum (a chalky mineral that is a major component of wallboard). These
layers are eventually buried by sediments. If the salt layers are
buried deeply enough, the pressure can cause them to flow. Salt has lower
density than the surrounding rock, so it tends to flow upwards, pushing
up the overlying layers of rock to form a dome. While many salt domes
retain a cap of the youngest rock layers at the surface, in some cases
the underlying salt extrudes all the way to the surface.
This astronaut photograph illustrates the varying character of
surfaces on Sir Bani Yas. The central mountains of Jebel Wahid (image
center) mark the location of the Sir Bani Yas salt dome. The dome has
breached the surface but exposed salt, primarily gypsum, is eroded,
leaving a rugged, insoluble cap made of fragments of the overlaying
sedimentary and volcanic rocks. Sand and silt derived from the Jebel
Wahid and surrounding gravel-covered areas form beaches along the outer
edge of the island.
Sir Bani Yas Island was the personal retreat of the late Sheikh
Zayed Bin Sultan Al Nahyan who was president of the UAE from 1971-2004.
He established a nature preserve on the island for animals native to
the Arabian Peninsula (including striped hyena, cheetah, oryx, ostrich,
and gazelle) that is now open to the public. The numerous orchard plots
that cover much of the island were part of a desert agricultural
research program also started by the late Sheikh. Tan graded areas
along the western and northeastern coast of the island (image bottom
and image left) may be revegetated with additional plots or developed
for other land uses.
Astronaut photograph ISS022-E-58538
was acquired on January 31, 2010, with a Nikon D3X digital camera
fitted with an 800mm lens, and is provided by the ISS Crew Earth
Observations experiment and Image Science & Analysis Laboratory,
Johnson Space Center. The image was taken by the Expedition 22 crew. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab
to help astronauts take pictures of Earth that will be of the greatest
value to scientists and the public, and to make those images freely
available on the Internet. Additional images taken by astronauts and
cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, NASA-JSC.