Archaeological Insights into the Past Climates of Fuerteventura
Fuerteventura, the second largest island in the Canary Islands, has a rich history characterized by changing climates and the adaptation of its inhabitants. Recently, extensive research conducted on neighboring Lanzarote has shed light on the climatic shifts that have taken place on Fuerteventura over time. This study reveals that while the island is now predominantly arid, it has not always been a desert. This article explores the evidence and interpretations behind these findings, highlighting the importance of understanding past climates for current environmental management.
Introduction to Fieldwork and Background
My fieldwork on Lanzarote provided valuable insights that can be partially transferred to Fuerteventura. Colleagues from my department have worked extensively on Fuerteventura, and their findings help paint a comprehensive picture of the island's climatic history. Both Lanzarote and Fuerteventura are relatively young, with Lanzarote being approximately 15 million years (myr) old and Fuerteventura about 22 million years old. This relative youth means that the major geological processes such as plate tectonics and latitude shifts played limited roles in shaping the islands' current environments. Instead, the key factors influencing climate have been temperature changes and dust accumulation from the nearby Sahara Desert.
Evidence of Eolian Sand Accumulation and Desert Formation
The research uncovered several key pieces of evidence supporting the climate's evolution on the islands. One prominent example is the presence of eolian sand, which has formed dune sands and silt "desert loess" deposits. Although these weak soils and soil sediments suggest a drier current climate, they do not necessarily indicate a continuous arid condition throughout history. Soil sediments form under specific environmental conditions, and their presence indicates that at some point, the climate was moister than it is today.
The most compelling evidence comes from sediment and soil analysis using optically stimulated luminescence (OSL) dating techniques. A specific profile from Fuerteventura illustrates this perfectly. This profile, including the sediment ages determined through OSL, shows the eolian sand accumulation and suggests that the island experienced varying climatic conditions over time.
Comparing Lanzarote and Fuerteventura
Your colleague's findings from Lanzarote further support the hypothesis that Fuerteventura was once greener. Both islands have a subsurface carbonate layer, indicated by white 'V' features, which bear witness to their wetter past. In a humid climate, carbonates would be leached into the groundwater, leaving the soil relatively carbonate-free. The presence of carbonate layers in the buried subsoils of Lanzarote and Fuerteventura suggests that these areas were once more humid than they are now.
The Sahara Desert's significant impact on the islands is another critical factor. Desert dust, rich in quartz grains, is easily reconstructed due to its distinct composition. This dust has accumulated over time, reflecting the changing climate and environmental conditions on the islands. The Sahara's proximity to Lanzarote and Fuerteventura means that the impact of this dust has been substantial and ongoing.
Implications and Future Research
Understanding the climatic history of Fuerteventura and Lanzarote has significant implications for modern environmental management. For instance, the findings suggest that the current arid conditions are not a permanent state but rather a more recent development. This knowledge can help in planning sustainable land use and water management strategies, taking into account the potential for future climate shifts.
Future research should focus on exploring further evidence of vegetation and soil formation during the moister periods. The absence of tree evidence to date suggests that the climate was too arid for tree growth. However, the presence of grass and herb-dominated vegetation indicates a semi-arid climate that supported diverse plant life. Continued interdisciplinary research involving geology, archaeology, and climatology will be crucial in unraveling the full spectrum of these climatic changes.
Conclusion
The climatic history of Fuerteventura, like that of Lanzarote, is complex and multifaceted. While the island is now predominantly arid, it has not always been a desert. The evidence from eolian sand accumulation, sediment and soil analysis, and the presence of carbonate layers provides a clear picture of a moister past. These findings not only enrich our understanding of the natural history of the Canary Islands but also offer valuable insights for current and future environmental management.
Keywords: Fuerteventura, Lanzarote, Desertification, Climatic Changes, Eolian Sand