GSA Today

Thirty-four documented archaeological sites, dated >5000 yr B.P. and located in and adjacent to marine deltas, are identified to evaluate early occupation of Holocene deltas worldwide. Modern marine deltas began to form from ~8500 to 6500 yr B.P., and our survey distinguishes at least 16 archaeological sites dated to ≥7000 yr B.P., which indicates that these resource-rich ecosystems were used by humans soon after their development. The model presented here links deceleration in rate of Holocene sea-level rise with the near-synchronous development of deltas and human occupation of these fertile plains. The integrated geological and archaeological database shows that conditions in and around deltas (accumulation of fertile soil, reliable water supply, perennial aquatic food sources, ease of travel and trade) were attractive to human immigration and settlement. Currently, rising sea level and land subsidence are principal natural phenomena affecting use of deltas, and humans remain ...

Recent drilling in the eastern Mediterranean Sea south of Cyprus has revealed important insights into fundamental tectonic processes associated with continental collision and ophiolite emplacement. A transect of four sites was drilled across the Africa-Eurasia plate boundary. The results show that the African plate, represented by the Eratosthenes Seamount, underwent rapid subsidence and related faulting in Pliocene-Pleistocene time. The driving force was tectonic loading by the Eurasian plate. In this area the leading edge is represented by the Troodos ophiolite. The breakup and subsidence history of the Eratosthenes Seamount, as revealed by drilling during Leg 160, is clearly linked with the emplacement of the Troodos ophiolite. This underwent strong surface uplift during active tectonic emplacement, associated with collision of the seamount with the Cyprus margin.

Uplift of the Eastern Cordillera in the northern Andes has been linked to orographic climate change and genesis of South America's largest river systems. The timing of initial uplift remains poorly constrained, with most estimates ranging from ca. 60 to ca. 5 Ma. New detrital zircon U-Pb ...