Madre de Dios Speleo 2008

Background

Just under half of Madre de Dios island is composed of karstic limestone of Permian and Carbonfierous age (260 to 350 million years old). The landscape is characterised by some of the most unusual and spectacular surface karst in the world. High annual rainfall of around 8 m together with the karstic nature of the limestone deposits has resulted in large- scale karren, shafts and dolines. Erosion rates of 10 mm a century are thought to be some of the highest in the world. Pioneering caving expeditions from France (1995, 1997, 2000, 2006) and Poland (2003) have discovered large-scale cave development beneath this landscape. Despite harsh weather conditions and difficulty in moving through the karstic terrain the French team have explored more than 8 km of cave passage with a maximum depth 280 m below the surface. There is, however, still huge potential for cave exploration on the island. The French are continuing land-based exploration from the south in early 2008. Our expedition will be boat-based and will aim to explore different areas, focussing on the coastal limestone areas in the north of Madre de Dios, but also other nearby limestone islands. Miners work seasonally on the south of the island, and it is at their outpost that the French expeditions are based, but reaching the northern parts of the island is difficult by land and hence these areas are rarely visited by anyone. We will liaise closely with this French expedition to ensure coordination of our exploratory and scientific work. We have been liaising with Charlie Porter, an American boat skipper with years’ of experience in the waters around Southern Chile. He has visited Madre de Dios, has found several caves himself, and has Chilean contacts who are able to show us the location of more cave entrances in areas that are apparently unexplored by Chilean or foreign cavers. The expedition will be based on Charlie Porter’s boat “Ocean Tramp”.

The caves on Madre de Dios and neighbouring islands are the most southerly in the world. They are therefore of great significance in climatological studies to investigate millennial-scale abrupt climate events and the linkages between climate changes in Antarctica and the rest of the world, and to predict future climate changes. Existing palynology and glacier studies from Southern Chile provide an insight into the region’s climate history (e.g. Sugden et al. 2005; Moreno et al. 2001). Palynological studies provide qualitative information on the temporal variation in vegetation types and glacial moraine studies provide local information on glacial advance and retreat but neither technique results in a detailed climate record. Past climate records captured in speleothems are a particularly powerful palaeoclimate archive because they offer high resolution and continuous records that can span thousands of years (Hu et al., 2005; Johnson et al., 2006). Our expedition will be particularly focused on searching for older fossil caves where there are speleothems that can be used for climatological study.