Overview. My research is focused on investigating the tectonics, stratigraphy, and volcanic deposits in the Afar Depression, Ethiopia. The area is significant for its exposures of fossiliferous sedimentary rocks from the Pliocene to Pleistocene (5.3 – 0.1 Ma) that are well known because they yield fossils and artifacts of early humans, including the Australopithecus afarensis specimens ‘Lucy’ and ‘Selam’ and the oldest stone tools. This region is also important because it lies in a triple rift junction between oceanic spreading centers (Red Sea and the Gulf of Aden) and continental rifting (Main Ethiopian Rift) and has been volcanically active for the past 35 million years.
After initial surveys of the geology and fossils by researchers in the 1970’s, research in the Ledi-Geraru project area resumed in 2002 lead by scientists at Arizona State University including Dr. Kaye Reed. The project now includes an international team of researchers that specialize in different fields including geology, paleoecology, paleoanthropology, and archaeology. I, along with the other geologists on our team, map and describe the sequences of sedimentary rocks and collect, analyze, and date volcanic ash layers (tuffs) that allow us to date and correlate the sedimentary rocks that contain fossils and artifacts.
The Ledi-Geraru Research Project is located in Afar, Ethiopia along the Awash River. Image: Erin DiMaggio
- Click Here to read my ‘Report from the Field’ blog written in 2013. It provides a glimpse into daily life working in the Afar.
- Click Here to read “Notes from the field” updated by researchers at the Institute of Human Origins and members of our team at Ledi-Geraru.
- The Ledi-Geraru Research Project
- The Ledi-Geraru Research Project at the ASU School of Human Evolution and Social Change
- Hadar Geoinformatics Project including link to the project ArcGis Server
Discovery of the oldest fossil of the genus Homo from the Ledi-Geraru project area
Two joint articles published on March 4th in the Journal Science (Sciencexpress)
Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia
Brian Villmoare, William , C, , , , , , and
Published online 4 March 2015 [DOI:10.1126/science.aaa1343]
Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar, Ethiopia
Erin N. DiMaggio, Christopher J. Campisano, John Rowan, Guillaume Dupont-Nivet, Alan L. Deino, Faysal Bibi, Margaret E. Lewis, Antoine Souron, Lars Werdelin, Kaye E. Reed, and J. Ramón Arrowsmith
Published online 4 March 2015 [DOI:10.1126/science.aaa1415]
Hominin mandible in the hands of Chelachew Seyoum shortly after discovery (photo: Brian Villmoare)
On January 29th, 2013 Chalachew Seyoum, a graduate student at ASU and part of the Ledi-Geraru research project, found a hominin mandible in a region called “Lee Adoyta” located near the Geraru drainage (see map).
The mandible was recovered from a layer of very fine sediment (silt) near the top of a hill, and this layer lies 10 meters directly above a tuff that we named the “Gurumaha Tuff”. Since we cannot directly date the fossil, we used a high precision radiometric dating technique called 40Ar/39Ar to date small crystals in the tuffs. We found that the Gurumaha Tuff is 2.82 million years old and by estimating about how long it takes sediment to accumulate the 10 meters from the tuff to the level the fossil was found, we determined that the hominin mandible is between 2.80 and 2.75 million years old. We also dated a tuff called the ‘Lee Adoyta Tuff’ to 2.67 million year old, which is faulted down in a hill just east of the hominin site. This date provides a minimum age constraint for the hominin fossil.
Location map of the 2.8 million year old Ledi-Geraru mandible along with other important discoveries made in the lower Awash Valley region. Erin DiMaggio
The discovery of a 2.8 million year old rock record in this part of the Afar that contains fossils, especially fossils of hominins, is really exciting! This has remained an enigmatic time period for both geology and fossil studies because much of the rock record from around this time was eroded long ago, or is incomplete in this part of the Afar. The rocks and fossils that we are studying at Ledi-Geraru allow us to shed light on not only the human lineage, but the geologic setting and environment in which early Homo lived.
Select articles covering the discovery:
- New York Times: Jawbone Fossil Fills a Gap in Early Human Evolution
- AAAS Science: Fossil pushes back human origins 400,000 years
- National Geographic: Oldest Human Fossil Found, Redrawing Family Tree
- Smithsonian Magazine: Oldest Human Fossil Unearthed in Ethiopia
- NBC News: Fresh Fossil Studies Rewrite the History of Humanity’s Genus Homo
- CJR: Why it’s difficult for East African journalists to cover scientific discoveries
- Penn State University: Earliest known fossil of the genus Homo dates to 2.8-2.75 Ma
- Arizona State University: Discovery of jaw by ASU team sheds light on early human ancestor
Paleontologists working at the site where the 2.8 million year old hominin was found. Photo: Erin DiMaggio
Photos from the Ledi-Geraru project area
Exposures along the Mille River of lake sediments with volcanic ash layers (thin white layers) that have been faulted. Photo: Erin DiMaggio
Ledi-Geraru field crew in 2013; missing Ramon Arrowsmith
