Italy's Neanderthal caves reveal fluctuations in Mediterranean sea level

The sea level fluctuations in the Tyrrhenian period and the presence of Neanderthal Man in the caves of Circeo and Gaeta: the results of the study provide important indications for the evaluation of the sea level rise caused by global warming.

Images of Grotta Guattari, during the collection of samples for the chronostratigraphic study by the
 researchers of the INGV and the Department of History of Tor Vergata [Credit: INGV]

The discovery of unexpected changes in the Mediterranean Sea in the Tyrrhenian period (124,000 - 80,000 years ago) is a useful element in the assessment of sea level rise as a result of melting ice caused by global warming. This is the result of the study conducted by a team of researchers from the National Institute of Geophysics and Volcanology (INGV) in collaboration with the Department of History of Tor Vergata University and the Superintendence of Archaeology, Fine Arts and Landscape for the provinces of FR, LT and RI, just published in Scientific Reports.

"The research", explains Fabrizio Marra, INGV researcher and co-author of the study, "deals with two apparently very different aspects: the oscillations in sea level during the Tyrrhenian period and the frequenting by Neanderthal Man at the caves that open on the coast between the Circeo promontory and Gaeta. In these caves", continues Marra, "numerous remains have been found concerning the human frequentation during the Palaeolithic period. Among these, an almost complete Neanderthal skull found at Grotta Guattari is the most important, together with a large number of flint tools. Moreover, the peculiar presence of tools made by Neanderthals using the seashells of the bivalve 'Callista chione', locally known as fasolaro, which is still widespread on the beaches of the Latium coast, has emerged".

Precisely thanks to the presence of a series of elements such as shells, bore holes of "lithodomic" organisms living in the cliffs and waterline grooves carved into the rock by the tide, these caves provide important indications of sea level oscillations linked to the last two glaciations.

Through the reconstruction of the surfaces of ancient sea terraces (T) and the re-examination of sea-level indicators
 (LdM) the ancient coastlines between Anzio and Gaeta (a, b, c) have been reconstructed. Particularly useful for
 the reconstruction were the beach and dune deposits present inside several caves that open on the cliffs between
 Circeo and Gaeta (c). A new dating made on a fossil shells in the locality of Quadrato has confirmed earlier
dates made by paleoanthropologists in Grotta Guattari and Grotta dei Moscerini. These two caves are
 in fact rich in evidence of Neanderthalian presence in periods when the sea level was close
 to their entrance [Credit: INGV]

"The Tyrrhenian Sea", adds the researcher, " marks the interglacial period between the last two glaciations 160,000 and 20,000 years ago respectively. During this period, after the sea had dropped to 120 metres below its current level due to the freezing of large masses of water at the poles, it rose rapidly during the end of the glacial period. Around 125,000 years ago," continues Marra, "the sea reached and exceeded the present level by about six metres. This was followed by two oscillations in which the sea level dropped again due to the sharp drop in temperature and then rose again, before "falling" again by more than one hundred metres during the last ice age.

The study has ascertained that during these two temporary ascents, which took place 100,000 and 80,000 years ago, the sea level reached heights close to the current one, in sharp contrast to what has been estimated so far through the theoretical calculation of the volumes of ice that formed and melted during this period".

Because of this, during these interglacial phases, the caves opened up on small beaches that were favoured by the Neanderthals. These caves provided them with the possibility of finding the shell fish on which they fed, then using the discarded shells to fashion small tools.

"The results achieved with this study are also important for the present day. This is because in assessing the expected sea level rise due to the melting of ice caused by global warming, this unexpected behaviour of the Mediterranean in past eras will necessarily have to be taken into account," concludes the researcher.

Source: INGV [trsl. TANN, July 30, 2020]

TANN

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