|A handful of members from the UK DeepCHALLA team|
East Africa, is home to the East African Rift (EAR) Valley, one of the most extensive active rifts on Earth. The EAR valley represents the formation of a new ocean, created by two slowly moving diverging continental plates. This has resulted in volcanic and seismic activity, as well as producing some of the world’s most dynamic and unique ecosystems including the EAR lakes. These lakes are some of the oldest, deepest and largest in the world. Thus, these lakes have sediment records millions to hundreds of thousands of years old, capturing long-term changes in their local and regional environment. In addition, past eruptions from volcanoes along the EAR emitted ash that not only is relatively easy to date but provided excellent preservation of the remains of our human ancestors and the megafauna they hunted. This resulted in the region being termed “the cradle of mankind”, globally important archaeological sites which have advanced our understanding on the evolution of our own and other species. During the AFQUA conference, attendees were lucky to visit such globally unique ecological and archaeological sites.
The international group of scientists working on DeepCHALLA are investigating ~250,000 years of environmental change using sediments retrieved from the bottom of Lake Challa, a steep-sided crater lake on the Kenyan, Tanzanian border, close to Mt Kilimanjaro. Whilst technically not considered an EAR lake, Challa’s creation is a result of the volcanic activity caused by rifting. Presentations and workshops were conducted by all four of the UK-based scientists working on the DeepCHALLA record, and involved how to produce reliable radiocarbon chronologies by Dr. Maarten Blaauw, Queens University Belfast and understanding the patterns and drivers of fires in Africa by Dr Daniele Colombaroli from Royal Holloway alongside others. Heather and Erin ran a workshop on how lake sediments can be used to understand natural hazards.
Alongside Erin, Heather spoke about how we can use fossilised algae from photosynthesisers (microscopic to larger plants) in lake sediments to understand climate and human impacts on lake ecological communities. Like many lakes globally, lakes in East Africa and those across the continent have been subject to climatic variability and pollution from the intensification of human activity and growing human populations Understanding the timing and magnitude of ecological change can help pinpoint impacts and causes of environmental modifications and ultimately guide where management should focus.
|Erin enjoying the volcaniclastic deposits of the dried up river bed found|
in the catchment of Lake Challa
This blog was written by Dr Heather Moorhouse, Diatom Isotope Research Technician working at Lancaster University, alongside the stable isotope facility at the British Geological Survey and Dr Catherine (Erin) Martin-Jones at the University of Cambridge.