Geologia Himalayana. Tra mito e realtà: Apalala il drago del fiume Swat

In popular Buddhist lore, Apalala was a serpent-god who ruled over the waters of the Swat River. The reliefs and artistic panels of Gandhāran art depict his submission to the Buddha, after which he ceased to rage and cause floods and droughts. Nestled between the Hindu Kush and the Himalayas, at the foot of Kohistan, Gandhāra corresponds to northwestern Pakistan. Gandhāra is its ancient name and refers to a vast area crisscrossed by major rivers, including the Swat. It was one of the centers for the spread of Buddhism, where, following Alexander the Great’s conquest, Buddhism spread alongside its art within the Indo-Greek kingdoms. The ancient city of Bazira lies at Barikot, an archaeological site in the middle Swat Valley. The site is currently being studied by the Italian archaeological mission in Pakistan, which has been active in the country for 70 years. Geo-archaeological evidence points to a complex and highly unstable fluvial dynamic. While the main valley of the Middle Swat is characterized by active sedimentation fueled by frequent floods, at Barikot and in the other side valleys, erosion and sedimentation have alternated, leading to the development of terraced surfaces. At Barikot, three orders of terraces developed following a phase of predominantly catastrophic sedimentation that lasted until around 1300–1200 BCE, filling the valley floor with thick silty flood deposits. This was followed by a phase of erosion and new settlements that developed after 1200 BCE. These were destroyed by a flood that led to the abandonment of the site for several centuries, from about 800 to 500 BCE, and to the silting up of the intermediate terrace. On this new surface, the city of Bazira was established and grew over a long period as the valley gradually eroded by a few meters. Thus, the geological evolution of Barikot suggests that the myth of Apalala may have a historical basis in major flood events that shaped the Swat Valley and its tributaries during the Holocene.