Grad Profile
Ancient, modern lakes hold clues to change

April 25, 2008

By Brett Ehalt

When asked why she chose to research animal-sediment interactions around ancient and modern lake environments, PhD student and paleo-ecologist Jenni Scott said this: “If we have knowledge of how geological processes have shaped landscapes over time and how animals have responded to those changing conditions, then we will be better able to consider the changes in the world that are happening now.”

Since beginning graduate studies in 2001, Scott has spent three summers in the Kenya Rift Valley. There, she explored (modern) Lakes Bogoria, Baringo, and Magadi, and learned much about the distribution of trace assemblages—that is, how the collection of animal burrows and footprints and their distribution around the lakes changes through time in relation to lake levels and water chemistry, and how they are influenced by hot springs.

Hot springs near the shoreline of saline Lake Bogoria, she explains, provide isolated areas of fresh water, enabling a higher diversity of plants and animals to live around them. If the lake level falls, and it becomes more saline, for example, the relative importance of the hot springs may become greater, and the survival of many animals may depend on the areas surrounding the hotsprings.

Scott also investigated ancient lake deposits in Kenya. In some of these deposits, thought to be saline in the Pleistocene era, Scott’s research group discovered hundreds of fossil hippopotamus footprints. Since hippos generally live in fresh water, the team was prompted to further research the formation of the footprint-preserving minerals and to deduce that, gradually, the area changed from a relatively fresh wetland to a dry soil with saline groundwater.

More recently, she has focused her studies on saline lakes specifically. “Not as much is known about the composition and distribution of trace fossils around closed, saline lakes when compared with other environments, like marine settings. Plus, lake-level fluctuations in saline lakes are more frequent and dramatic than in other lake types, and because of this, they are a sort of natural laboratory, with changes in environments somewhat compressed in time. That makes things interesting.”

Scott has also extended her research to include much older lake deposits in North America. For the last four years, she has spent every June exploring the Eocene Green River Formation of Wyoming, which is about 50 million years old and known mainly for its body fossils – fish, snakes, birds, and the like.

Curiously, it is through her work in Wyoming that Scott has gained a “broader perspective” on the Kenyan record, and vice versa.

“The rocks in Wyoming reveal clues as to how traces are preserved in a different, but similar, set of environments and over a greater amount of time. Each new clue or piece of information is then applied to modern settings in order to better understand the processes involved. At the same time, ideas learned in modern settings are used to help us interpret ancient settings.”

Scott plans to return to Wyoming this summer and to complete her project by next year. Meanwhile, she intends to enjoy every step along the way. “My studies have allowed me to learn about animal behaviour and ecology, but in geological time and context. It’s the best of both worlds.”

Brette Ehalt writes profiles of grad students for the College of Graduate Studies and Research.