Yemen is extremely
arid - however, in the past it was more humid and wet, enabling large river
systems to evolve and carve out the deep and spectacular gorges and wadis (dried
out river beds) seen in this image. The erosion has revealed many contrasting
rock types.
This image has been processed to exaggerate this effect, producing many shades
of red,
pink, purple which make geological mapping easier and more cost-effective.
South-eastern Yemen (left)
At one time Yemen and Somalia were linked together, but have now drifted apart as the
Gulf of Aden gets bigger and more ocean floor is created. The effects of this extension
affected the interior of Yemen, producing many east-west trending geological faults that
are expressed here as steep, shaded slopes that face to the north. The faults are often
the target for geological exploration, as they help trap large quantities of oil and gas.
Zagros Mountains, Iran (right)
The Zagros Mountains
of Iran were formed as Arabia collided with Southern Eurasia. The centre of
this colour-enhanced image shows an anticline that runs E-W. The dark
grey
features are diapirs - i.e. masses of viscous rock salt that are very
buoyant and, under the right conditions rise to the surface, spilling and spreading
out like a glacier. The
presence of salt in the region is important as it stops oil escaping to the surface
in large
quantities, trapping it deep underground, from where it can be extracted.
Sichuan Basin, China (left)
The NE-SW trending
ridges in this image from China are anticlinal folds developed in the
earth's crust as a result of plate collision and compression. Geologists map
these folds
and the lowlands between them formed by synclinal folds, as they are often
the areas where
oil or gas are found in commercial quantities.
