Page 195 - Life & Land Use on the Bahrain Islands (Curtis E Larsen)

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high sea levels, as much as 150 m above the present, covered much of the Arabian
coastal plain leaving a series of raised coastal landforms at various places along
the coast. Coastal terraces have been described for Saudi Arabia by Holm (1960),
Powers et al. (1966), and al-Sayari and Zotl (1978) and for the Trucial Coast by Lees
(1928).
In general terms, when Pleistocene sea levels were high, the climate was
apparently more moist than it is today, as evidenced by the deposit of coarse
alluvial gravels at the mouths of various wadis. Kassler (1973) suggests that these
alluvial gravels are graded to a sea level 90 meters above the present; care should
be used however, in assigning absolute elevations to such early sea level stands
based solely upon terrace gradients. As Butzer and Hansen (1968) have shown along
the Red Sea, terrace gradients can be quite deceptive. In addition, subsidence
noted along normal faults in the Gulf of Bahrain took place after the deposit of
these gravels, complicating their interpretation.
The most comprehensive analysis of landform development along the
eastern Arabian coast is included in KasslerTs discussion of the drowned topography
of the Arabian Gulf. On the basis of bathymetric and sparker profiles, it has been
possible to identify a network of submerged river valleys cut during periods of
subaerial erosion. The relationship of these valleys to submerged coastal terraces
indicates that the maximum development of rivers and wadis occurred in concert
with retreat of the sea during Pleistocene glaciations in the northern hemisphere.
During the Late Pleistocene to Holocene rise in sea level, which began about 18,000
years ago, coastal platforms were cut into a topography previously dominated by
fluvial erosion. Stream channels from these periods of greater stream activity can
be traced as deep as the lowest submerged platforms and as far as the mouth of the
Gulf of Oman. Kassler indicates that these stream channels were formed at a
single eustatic low sea level. The present submarine landscape of the Arabian Gulf
is the result of only a few thousand years of subaerial erosion and is therefore
juvenile in terms of morphology. Although the drainage pattern from the Arabian
coast is dendritic and the drain is northeastward down the structural slope of the
Arabian Peninsula, local internal drainage also took place. One of these areas was
the Gulf of Bahrain.