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 language | English |
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Pages (from-to) | 3152-3166 |
Number of pages | 15 |
Journal | Sedimentology |
Volume | 67 |
Issue number | 6 |
DOIs | |
State | Published - 1 Oct 2020 |
Bibliographical note
Funding Information:We gratefully acknowledge the support of the Interuniversity Institute for Marine Sciences in Eilat, Israel. This work was supported by Schulich Foundation, Israeli Ministry of Interior, the Admiral Yohay Ben-Nun Foundation-NAF-IOLR, and Sir Mick Davis. We would like to thank Dr Pedro Costa and an anonymous reviewer for their careful reading and their constructive remarks. Thank you to fellow laboratory group members of MGM laboratory, in particular A. Mathalon and Sedimentology Laboratory Manager Nimer Taha.
Funding Information:
We gratefully acknowledge the support of the Interuniversity Institute for Marine Sciences in Eilat, Israel. This work was supported by Schulich Foundation, Israeli Ministry of Interior, and Sir Mick Davis. We would like to thank Dr Pedro Costa and an anonymous reviewer for their careful reading and their constructive remarks. Thank you to fellow laboratory group members of MGM laboratory, in particular A. Mathalon and Sedimentology Laboratory Manager Nimer Taha.
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