UAE's Miocene rocks and their fossil record
Miocene rocks have been divided into two formations - the Baynunah and
the Shuwaihat Formations named after the places where they are best
exposed. The Shuwaihat Formation outcrops at sea level in some of the
coastal exposures and mainly consists of fossilised aeolian sands. These
rocks seem to lack any fossils that can be used for dating purposes,
but by careful stratigraphic work it is believed that rocks of the Shuwaihat
Formation might be of the same age as similar rocks found in Saudi Arabia.
Thus, their age might be about 14 million years old. Confirming evidence
for this date, plus or minus a few million years, comes from detailed
analysis of the imprint of the earth's magnetic field on the iron minerals
in the sandstone: magnetochronology.
After the aeolian sands of the Shuwaihat Formation had become rock,
a regional river system evolved. The sands, gravels and clays deposited
by this river form the Baynunah Formation that overlies the Shuwaihat
Formation in the Western Region. The Baynunah Formation contains fossils
and, so far, four species of invertebrates; two species of plants; three
species of fish; eight species of reptiles; two species of birds and
31 species of mammals have been identified. Of these one species of
fish and two mammal species are new to science. It is likely that the
fossils from Abu Dhabi represent animals that lived during a time period
of between 6 and 8 million years ago.