For several months each year I work in central Africa collecting sediment cores and fossils from a large rift lake, Lake Tanganyika. Periodically my nonscientist friends ask me why I do this. They usually mean both ‘‘why would someone collect mud from the bottom of a lake’’? and perhaps as an even greater challenge to my sanity, ‘‘why would one travel halfway around the world to do this’’? The answer to these questions (and the theme of this book) is deceptively simple. Paleolimnologists study lake deposits because they provide science with archives of earth and ecosystem history that are both highly resolved in time and of long duration. In the particular case of Lake Tanganyika, this combination, in principle, permits us to study events as closely spaced in time as annual events over the lake’s 10-million-year history. Few other records of earth history beyond those found in lake muds provide this combination of duration and resolution. The range of questions that can be examined with these archives is enormous. Paleolimnologists provide constraints on the timing of past climate change, determine rates of evolutionary change in species, and investigate the timing of pollutant introduction into watersheds. One might reasonably ask what good could come from trying to synthesize these disparate questions. I believe that the unifying factor behind all of these fields of study lies in the character of lake sediment archives. Lakes are attractive targets for study by such different fields of investigation because of the special nature of their depositional environment. Considering the contents of lake archives and their characteristics is the best place to start thinking about what makes paleolimnology a distinctive discipline. . . . What Are Lake Archives? . . . An archive is a singularly appropriate term to describe the foundations of paleolimnological research. The term archive can refer both to a historical record, its content, and to the place where such records are housed, its container.
Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange
