Droughts in the desert: Medieval Warm Period associated with coarse sediment layers in the Gulf of Aqaba-Eilat, Red Sea

Akos Kalman, Timor Katz, Paul Hill, Beverly Goodman-Tchernov

Research output: Contribution to journalArticlepeer-review

Abstract

Prolonged droughts can cause environmental stress, even in ecosystems that are already adapted to dry conditions. In these areas life greatly depends on rare, sporadic rainfall events that can produce flash floods. Today, urban expansion, population growth and development are occurring worldwide, including along hyperarid coastlines, an ecological zone on the extreme of habitability. In such places, the absence of the already limited precipitation can lead to long-lasting damage, and recognizing drought conditions in the past is useful for planning. Recognizing droughts, however, is challenging because they are not known as depositional events, and therefore may be under-recognized in the sedimentological record. Floods in these hyperarid deserts carry eroded sediments and deposit them in either terrestrial or marine terminal basins. In the hyperarid (ca 30 mm rain per year) desert surrounding the northern Gulf of Aqaba-Eilat some flash floods reach the sea and deposit alluvial sediments (mostly silt and clay) on the shelf. Following a recent 17 year drought period (1995 to 2012) a coarser surface layer was recognized offshore the outlet of an ephemeral river, despite the lack of incoming flood material. This coarsened layer resulted from a prolonged period wherein mixing and winnowing of fine particles at the surface was not interrupted by recurrent flash floods. In the bottom of two sediment cores collected from the same shelf, a similarly coarsened layer was observed. The terminal level of this deep coarse layer was dated to ca 660 yr bp, corresponding with the end of the Medieval Warm Period (ca 1350 ad). These findings suggest that the medieval anomaly resulted in a prolonged drought period in this already arid region. These results present a new interpretation of grain-size distribution records that provides a means to reconstruct drought histories in hyperarid regions globally.

Original languageEnglish
Pages (from-to)3152-3166
Number of pages15
JournalSedimentology
Volume67
Issue number6
DOIs
StatePublished - 1 Oct 2020

Bibliographical note

Publisher Copyright:
© 2020 The Authors. Sedimentology © 2020 International Association of Sedimentologists

Keywords

  • Droughts
  • Medieval Warm Period
  • Red Sea
  • flash floods
  • sedimentology
  • winnowing

ASJC Scopus subject areas

  • Geology
  • Stratigraphy

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