Page 197 - Life & Land Use on the Bahrain Islands (Curtis E Larsen)

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are recognized in the field by marine fossils associated with the various steplike
terraces, and can be recognized in these approximate elevations on the east coast
of Qatar (Perthuisot 1980, Vita-Finzi 1978).
An historical appraisal for the pattern of eustatic sea level changes during
the Pleistocene can be gained from Fairbridge (1961), Woldstedt (1961) and Butzer
(1975). Studies of the Mediterranean coast have furnished evidence for multiple
interglacial sea levels during the Pleistocene as high as 30-100 m above the
present. Fairbridge (1961) presented a questionable synthesis of evidence for the
Pleistocene, which involved three extended periods of high sea level. A first
alternative interpretation correlated high sea level stands with three major
Pleistocene interglacial periods, so that these postulated high sea levels were
shown to decrease in elevation from the Glinz/Mindel (+100 m), the Mindel/Riss
(+30-40 m), and the Riss/Wlfrm (+2-12 m). The second alternative interpretation
presented the same three major high sea level stands on a compressed time scale.
More precise dating of Pleistocene events has taken place since 1961 and has led to
a revision of both of these possibilities. Butzer (1975), for example, has shown at
least a five-fold division of high sea levels at elevations similar to those of
Fairbridge, but related to events that occurred during the past 400,000 years.
Direct worldwide correlations of sea level stands are hazardous. Nonetheless, high
sea levels at elevations similar to those recorded in the Mediterranean have
influenced the Arabian coast.
The higher Arabian marine terraces between 15 m and 70 m are covered
with "duricrusts," a cement derived from the weathering of various carbonate rocks
and evaporites in arid or semiarid environments (Goudie 1973). Such protective
crusts are missing from the three lower terraces, suggesting younger ages. Felber
et al. (1978:55) obtained a preliminary age for the 10 m terrace, where oyster shells
collected from below the terrace surface yielded a minimum age of 38,800 B.P.
TTiese writers relate this stand to the middle Wlk*m Interstadial (40,000-26,000
B.P*), but a similar date (39,800 B.P.) was reported from a 25-30 m terrace on the
Qatar Peninsula by Kapel (1967). Thus, caution should be used in assigning absolute
ages to any of these terraces until more refined dating or a better understanding of
the tectonics of the region are available.