Jebel Irhoud

Jebel Irhoud (Arabic: جبل إيغود, Moroccan Arabic: žbəl iġud) or Adrar n Ighoud (Standard Moroccan Tamazight: ⴰⴷⵔⴰⵔ ⵏ ⵉⵖⵓⴷ, romanized: Adrar n Iɣud), is an archaeological site in Morocco located just north of the town of Tlet Ighoud in Youssoufia Province, approximately 50 km (30 mi) south-east of the city of Safi.

It is noted for the hominin fossils that have been found there since the discovery of the site in 1961. Originally thought to be Neanderthals, the specimens have since been assigned to Homo sapiens and, as reported in 2017, have been dated to a "weighted average age" of 315,000 years ago. This makes the remains by far the earliest known examples of Homo sapiens, and suggests that rather than arising in East Africa approximately 200,000 years ago, modern humans have been present across the length of Africa 100,000 years earlier.

The site is the remnant of a solutional cave filled with 8 metres (26 ft) of deposits from the Pleistocene era, located on the eastern side of a karstic outcrop of limestone at an elevation of 562 metres (1,844 ft). It was discovered in 1961 when the area was being mined for the mineral baryte. A miner discovered a skull in the wall of the cave, extracted it, and gave it to an engineer, who kept it as a souvenir for a time. Eventually, it was handed over to the University of Rabat, which organized a joint French-Moroccan expedition to the site that was headed by anthropologist Émile Ennouchi.

Ennouchi and his team began their excavation of Jebel Irhoud in 1961. Before beginning excavation, Ennouchi's team removed 2000 tons of debris that covered the archaeological layers using low-level explosives. The excavation completed by Ennouchi's team used horizontal arbitrary 50 cm stratigraphic layers, or spits. Ennouchi's team identified the remains of approximately 30 species of mammals, some of which are associated with the Middle Pleistocene, but the stratigraphic provenance of these remains is unknown. During the Ennouchi excavations, two hominin fossils, Irhoud 2 and Irhoud 3, were discovered and identified as an adult and a child. The associated lithic technology was identified as Mousterian, leading the Irhoud hominins to initially be identified as Neanderthals. Ennouchi's team was also the first to attempt to date the site. They used radiocarbon dating, but their results revealed that the site was older than 50,000 years and was thus beyond the measurement capabilities of radiocarbon dating.

Another excavation was carried out by Jacques Tixier and Roger de Bayle des Hermens in 1967 and 1969, during which 22 layers were identified in the cave in search of more hominin fossils. Irhoud 4 and 5 were identified during these excavations and were the first human remains found within a known stratigraphic context at the site, and were found in association with the Levallois Mousterian tool industry.

Jean-Jacque Hublin conducted more recent excavations beginning in 2004. These excavations continued the work of the 1960s excavations, performing a more detailed study of site stratigraphy and context. It was during these excavations that Irhoud 10 and Irhoud 11 were discovered, both of which were identified as adults. Recent work identifies the Jebel Irhoud individuals as early members of the H. sapiens clade.

The site's stratigraphic layers were originally defined during the excavations in the late 1980s. Differently defined stratigraphic layers were identified during more recent research, this time using geological principles. A description of the more recent site stratigraphy is as follows: Layers 1-3 do not contain much archaeological material, layers 4-6 contain some archaeological material (lithic tools) and zooarchaeological remains (primarily Gazella species), Layer 7 contains sediment described as "cemented" and contains a higher density of archaeological materials (lithic tools, some burnt) and zooarchaeological remains (primarily bovids) than the upper layers and corresponds to layers where the first Jebel Irhoud fossils were found.

Jebel Irhoud is a site with much geological diversity, including Triassic formations and Charkarkar cave, and Ganntour phosphate deposits. The current geomorphology of Jebel Irhoud was created during an event called the Hercynian orogeny. This event occurred between 310 and 280 Ma and created westward vergent folds. Three primary geological formation contributing to the Jebel Irhoud landscape: (1) Barite veins, (2) zones of barite or "substitution," and (3) karst deposits.