Maria A. Rodrigo and Francesc Mesquita, researchers at the Cavanilles Institute of Biodiversity and Evolutionary Biology (ICBiBE), of the scientific area of the University of Valencia Science Park (PCUV), have participated in the discovery that volcanic activity in La Garrotxa (Girona) extended until only 8,300 years ago (it was thought that volcanism ceased about 13,000 years ago), which is the most recent chapter of this phenomenon in the entire Iberian Peninsula. The results have been published in the prestigious journals The Holocene and Scientific Reports.
The study, which also involves the Cavanilles Institute of Biodiversity and Evolutionary Biology (ICBiBE), located at the University of Valencia Science Park (PCUV), the University of Burgos, IPHES-CERCA, IDAEA-CSIC, the Autonomous University of Barcelona and the University of Montpellier, has revealed very interesting and unprecedented data on a borehole 14 meters deep in Vall d'en Bas (Girona), the Autonomous University of Barcelona and the University of Montpellier, has been carried out on a 14-meter deep borehole in the Vall d'en Bas (Girona) and has revealed very interesting and unpublished data on the paleoclimatic and paleoenvironmental evolution of the Volcanic Field of La Garrotxa (Girona).
"We have been able to reconstruct the paleoclimatic evolution of the last 13,000 years of the NE Iberian Peninsula, the volcanism of La Garrotxa, and the impact of these eruptions on plant and lake ecosystems and on the Mesolithic human populations of the area," say Francesc Mesquita and Maria A. Rodrigo.
Thus, in the area closest to the volcanic activity zone (up to 50 km) and during the eruption events, different processes such as lava flows, deposit of volcanic materials, ash rain, gas emanation, aerosols, pyroclastic flows and earthquakes, affected flora and fauna, as well as air and water quality, and constituted a danger for human populations. In this sense, and from the study of nearby archaeological sites, it is observed that the nearest hunter-gatherer populations left the area temporarily during periods of high volcanic activity, and then returned in times of calm, which demonstrates a high capacity for reorganization and adaptation.
"We have been able to reconstruct the paleoclimatic evolution of the last 13,000 years of the NE Iberian Peninsula, the volcanism of La Garrotxa, and the impact of these eruptions on plant and lake ecosystems and on the Mesolithic human populations of the area," Francesc Mesquita and Maria A. Rodrigo, researchers at ICBiBE
Remains of carophyte algae present in the lake sediments studied. Oospores of these macroalgae coated with calcium carbonate (gyrogonites). Photograph: Maria A. Rodrigo
This volcanic activity caused several volcanic lava flows to obstruct the Fluvià river valley near Olot and a large lake was formed in the plain known today as Pla de les Preses. The sedimentary sequence of the studied borehole records local and regional signals related to the geomorphological, paleoclimatological and volcanic dynamics of the volcanic field of La Garrotxa.
The geological and biological indicators analyzed (aquatic organisms, pollen record, sedimentology and geochemistry) report mainly local hydrological variations, which have been related to the main climatic trends of the Holocene and late Pleistocene, including several abrupt climatic changes that offer clues about the processes that could be triggered in the context of the current global warming.
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