Archaeologists say Genovesa Cave Discovered in Mallorca, the main Balearic island and the Mediterranean's sixth largest, the find suggests that humans settled in the western Mediterranean much earlier than previously thought.
5,600-year-old underwater stone bridge in Genovesa Cave, Mallorca, Spain. Image courtesy of R. Landreth.
Limited archaeological evidence makes it difficult to reconstruct early human colonization of the Balearic Islands in the western Mediterranean.
By studying the 7.7-metre (25-foot) submerged bridge, Professor Bogdan Onak of the University of South Florida and his colleagues were able to provide compelling evidence of prior human activity within Genovesa Cave.
“The presence of this underwater bridge and other artefacts indicates a high level of activity and suggests that early settlers were aware of the cave's water resources and strategically built infrastructure to navigate through them,” Prof Onak said.
Genovesa Cave, located near the coast of Mallorca, has had parts of its passage flooded by rising sea levels and has clear calcite deposits when sea levels were higher.
These layers, along with the light-colored bands on the submerged bridge, act as markers to precisely track historical sea-level changes and pinpoint the date of the bridge's construction.
Previous studies had suggested a human presence at the site as far back as 9,000 years ago, but inconsistencies in nearby carbon-dated bones, pottery and other evidence, as well as poor preservation, had left the findings in doubt.
Recent studies have used charcoal, ash and bones found on the island to create a timeline of human settlement dating back about 4,400 years ago.
This allows the timeline of human presence to coincide with important environmental events, such as the extinction of the goat antelope. Myotragus balearix.
By analysing the bridge's mineral overgrowths and the height of the bridge's colour bands, the authors found that the bridge was built around 6,000 years ago – more than 2,000 years older than previous estimates, narrowing the gap in the timelines between eastern and western Mediterranean settlements.
“The history of the bridge's construction appears to be closely linked to the rapid Holocene sea-level rise just before 6,000 years ago and the brief period of sea-level stillness that caused parts of the upper part of the cave to be flooded,” the researchers said.
“Our chronology shows that sea-level rise stopped and stabilized for several hundred years, between 5,964 and 5,359 years ago. During this time, so-called phreatic expansions of speleothems (POS) formed in the cave lake and the characteristic 'bathtub ring' formed on the bridge.”
“Construction of the bridge probably began early in this period, as it was needed to cross the 0.25 metre deep lake, but it must have been completed before 5,600 years ago, when the upper part of the bridge was submerged.”
“Evidence suggests that humans constructed a cobblestone path and a sturdy bridge leading to the cave's water pool, facilitating access to the only dry part of the cave, located in the Sala d'Entrada across the lake.”
“The exact reason these structures in Genovesa Cave were built remains unclear.”
“However, the dating constraints imposed by the depth of the bridge, and the similar depths at which the POS and colour marks are found, support the idea that early humans were present on the island by 5,600 years ago, potentially extending the date back to 6,000 years ago.”
a paper A paper describing the findings was published in the journal Neurology today. Communication Earth and the Environment.
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BP Onac others2024. An underwater bridge built at least 5,600 years ago marks early human arrival on the Spanish island of Mallorca. Community Global Environment 5, 457; doi: 10.1038/s43247-024-01584-4
Source: www.sci.news
