About
22
Publications
11,302
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
179
Citations
Introduction
Current institution
Additional affiliations
December 2022 - November 2024
September 2017 - October 2022
September 2011 - September 2016
Publications
Publications (22)
Abundant geomorphological, biological, and isotopic records show that Arabia repeatedly underwent significant climate-driven environmental changes during late Quaternary humid periods. Precisely mapping how the enhancement and expansion of the African Monsoon during these humid periods have affected landscape evolution and human occupation dynamics...
The first billion years of Martian geologic history consisted of surface environments and landscapes dramatically different from those seen today, with flowing liquid water sculpting river channels and ponding to form bodies of water. However, the hydro‐climatic context, the frequency, and the duration under which these systems existed remain uncer...
A widely hypothesized but complex transition from widespread fluvial activity to predominantly aeolian processes is inferred on Mars based on remote sensing data observations of ancient landforms. However, the lack of analysis of in situ martian fluvial deposits hinders our understanding of the flow regime nature and sustainability of the martian f...
Ancient depositional rivers in arid regions (now expressed as ridges) host important repositories of past surface processes that can be used to infer past climates that sculpted the surface of both Earth and Mars. However, how frequent, how sustained, and under what climatic regimes these systems survived is hindered by the lack of field and labora...
The late Miocene Messinian salinity crisis was an evaporitic episode that occurred throughout the Mediterranean; it concluded with a transition from hypersaline to fresher-water “lake sea” (Lago Mare) conditions prior to the Pliocene. Whereas numerous researchers propose that Lago Mare sediments accumulated in a Mediterranean-wide lake filled with...
During the Quaternary period, the eastern Sahara's hydroclimate oscillated between wet and dry intervals. These oscillations caused drastic changes in precipitation rates, often associated with ancient human migrations. In particular, significant migration of riparian populations from the Nile Valley to the west and northwestward of the Sahara occu...
Orbiting and landed spacecraft have provided vast amounts of data on fluvial and fluvial-related landforms and sediments on Mars. One variant of these landforms consists of ridges interpreted to be remnants of ancient fluvial activity, observed at thousands of Martian locales, suggesting extensive precipitation and runoff on early Mars. The importa...
Throughout the last 65,000 years, there have been several brief periods of increased temperatures and precipitation over the eastern Sahara. These periods have been constrained by numerous proxies including: palaeodischarge and sediment-load estimates of the Nile River, cave speleothems, dust fluxes, fossil groundwater, marine sediments, and recons...
Data from orbiting and landed spacecraft have provided vast amounts of information regarding fluvial and fluvial-related landforms and sediments on Mars. One variant of these landforms are sinuous ridges that have been interpreted to be remnant evidence for ancient fluvial activity, observed at hundreds of martian locales. In order to further under...
During the Cenozoic Era, the Egyptian Sahara was the site of fluvial activity in a succession of at least three main drainage systems, including the Gilf System (40–16 Ma ago), the Qena System (24–6 Ma ago), and the Nile (30 Ma ago to present). These systems developed as a response to wet conditions, the dramatic events of tectonic activity in the...
Palaeodischarge and sediment load estimates of the Nile River, cave speleothems, dust fluxes, fossil groundwater, and abrupt fluctuations of lake levels suggest climate oscillation during the Late Quaternary over the eastern Sahara (e.g., Foucault and Stanley, 1989; Hoffmann et al., 2016). In the southern part of the Egyptian Sahara, remnants of La...
Palaeodischarge and sediment load estimates of the Nile River, cave speleothems, dust fluxes, fossil groundwater, and abrupt fluctuations of lake levels suggest climate oscillation during the Late Quaternary over the eastern Sahara (e.g., Foucault and Stanley, 1989; Hoffmann et al., 2016). In the southern part of the Egyptian Sahara, remnants of La...
Valley networks are the main fluvial erosional landforms that document the extensive fluvial history of early Mars. Hundreds of examples of sinuous ridges are topographically inverted due to eolian deflation. The sedimentary structures of those landforms have the potential to record a rich history about their respective depositional environments. T...
During the Late Pleistocene, several studies have identified climate oscillations in North Africa based on changes of paleodischarge and sediment loads from the Atbara, Blue Nile and White Nile and from cave speleothems in northern Africa and southern Europe (Foucault and Stanley, 1989; Hoffmann et al., 2016). These studies concluded that climate o...
Based on planimetric patterns, more than 200 sites of sinuous ridges have been identified on Mars from spacecraft images, including MOC (0.5-12 m/pixel), THEMIS IR (100m/pixel), VIS (18-36 m/pixel), CTX (~6 m/pixel), and HiRISE (~0.3 m/pixel), and the list continues to grow (Williams, 2007; Williams et al., 2007; Williams et al., 2011; Davis et al....
The Nile Valley between the Second Cataract at Wadi Halfa and the First Cataract at Aswan has been inundated behind two dams – the Aswan Dam, first built in 1902, and the High Dam (Sa'ad el A'ali), that blocked the flow of the Nile in 1964. The anticipated loss of archeological monuments in Lake Nasser, the reservoir behind the High Dam, initiated...
