The appropriate group to review this topic is an Interdisciplinary Panel of Holocene Studies Experts (Historical Geographers, Quaternary Geologists, and Archaeologists).
Abstract
This analysis details significant, rapid geographical and climatic shifts that occurred during the early stages of human civilization, post-Last Glacial Maximum (LGM). The three primary areas examined are the Persian Gulf, the Sahara Desert, and the Black Sea. Changes in sea level and fluvial sediment deposition caused major coastal reconfiguration in Mesopotamia, exemplified by the shift of Ur from a coastal city to an inland ruin. The transformation of the Sahara into a massive savanna (the African Humid Period, 9th to 4th millennium BC) is attributed to Milankovitch cycles increasing Northern Hemisphere summer insolation, which strengthened monsoon systems. This humid period ended abruptly, potentially exacerbated by human grazing practices. Finally, the Black Sea Deluge Hypothesis is presented, suggesting the catastrophic or gradual inundation of a former freshwater lake (the Neoyukinian lake) by rising Mediterranean sea levels after the LGM, an event that has been linked thematically to historical flood myths.
Holocene Paleogeography and Anthropogenic Intersection
0:02 Rapid Holocene Changes: The face of the Earth changed significantly in the few thousand years following the Last Glacial Maximum (LGM), concurrent with the development of farming and city-building civilizations.
0:44 The Persian Gulf Recession and Silting: The ancient city of Ur (built 6,000 years ago in modern Iraq) was originally a bustling port on the Persian Gulf coast. During the LGM, sea levels were up to 130 meters lower, and the Persian Gulf did not exist as a marine body. Its subsequent filling and gradual recession are attributed to the deposition of silt and sediments carried by the Tigris and Euphrates rivers, a process also observed at historical ports like Ostia (Rome) and Ephesus.
1:44 Mechanism of Coastal Change: Silt and sediments, washed upriver, fall out of suspension where fast-flowing river water meets the slower ocean, forming deltas and significantly altering coastlines over relatively short timescales.
2:53 The Green Sahara (African Humid Period): Cave paintings in Tassili N'Ajjer (Southern Algeria) depicting giraffes and oxen confirm the Sahara was previously a savanna. The Sahara was a desert during the LGM, turning green during the 9th millennium BC and reverting to desert by the 4th millennium BC.
3:37 Driving Climatic Mechanism (Milankovitch Cycles): This rapid change is explained by Milankovitch cycles—periodic variations in Earth's orbit and axial tilt—which influenced the amount of solar radiation hitting the Northern Hemisphere during summer.
5:00 Orbital Parameters and Monsoons: Approximately 10,000 years ago, Earth reached its perihelion (closest point to the sun) during the Northern Hemisphere summer, increasing insolation. This strengthened the monsoon winds, leading to higher rainfall across Northern Africa.
5:39 Savanna Landscape and Human Impact: The “green” period created a giant savanna dotted with lakes (like Mega Chad), supporting pastoral and agricultural societies. A climate shift around 3000 BC moved the rains southward. This process of desertification may have been exacerbated by human activity (grazing animals creating a dust bowl), occurring rapidly (100–200 years).
7:03 The Black Sea Deluge Hypothesis: This theory, considered controversial (a hypothesis, not a proven theory), concerns the filling of the Black Sea basin. During the LGM, the lower sea levels severed the connection via the Bosphorus and Dardanelles straits, leaving the Black Sea as a smaller, semi-freshwater lake (the Neoyukinian lake).
8:15 Proposed Inundation Event: As global ice melted and sea levels rose, salty Mediterranean water eventually breached the straits, catastrophically flooding the area, or alternatively, gradually trickling in.
9:02 Dating Controversy: Proposed dates for the Black Sea inundation range from 5600 BC (original papers) to a revised 6800 BC, or even as far back as 12,000 BC.
9:18 Links to Flood Myths: The timing of this event has frequently been linked to human great flood myths, such as those involving the biblical Noah or the Mesopotamian Utnapishtim. However, no human ruins or artifacts have been recovered from the formerly dry shelf areas of the Black Sea.