In 1978, a graduate student named Kerry Kelts stood on the deck of the Glomar Challenger in the Gulf of California and watched a new type of corer at work at Deep Sea Drilling Project (DSDP) Site 480. It was a hydraulic piston corer, which for the first time could produce long, clean cores from the geologically young soft mud at the surface of the seafloor. A whole new part of the geologic record was thrown open to detailed study. At that moment, Kelts was seized by a dream of using this technology—a drillship with hydraulic coring—to study lakes.
Geology of Lakes
Lakes are infants compared to the ocean, which is older than 100 million years in many regions. No lake is older than Baikal, in Siberia, and its history goes back to the early Miocene some 25 million years ago. But lakes are the best places to study the environment of the continents in recent geologic time. In our race against time to learn more about the global climate system, lakes are a treasure trove of data.
Lakes are young because they're always temporary features: either they fill up with sediment, or their outlet stream erodes downward until they drain dry. The lives of small ponds are measured in thousands of years. Even some very large lakes, like the Great Lakes between the USA and Canada, formed only during the current ice ages.
Lakes as Environmental Recorders
Nevertheless these lakes preserve important environmental evidence. The mud on their bottoms contains pollen grains from the surrounding vegetation plus different species of microorganisms that lived in their waters. As recorders of the local ecology, lakes have always been of interest to limnologists, who are mostly biological specialists. But when lake muds are used to infer temperature and rainfall in the past, a branch of geology—paleoclimatology—comes into play.
In many of these lakes, sediments form annual layers called varves that enable us to compile climatic histories of extraordinary detail. The best lacustrine records, therefore, are as good as the cores from the polar ice caps for studying ancient climates. A systematic program of coring lake beds can fill wide gaps in our knowledge of regional paleoclimates.
The minerals in lake muds offer still more insights. When vegetation is scant, more eroded sediment enters a lake, and the types of weathering and erosion that occur in dry times can be matched to the mineral record. Prevailing winds may change, watering different areas of bedrock and changing the balance of minerals washing into the lake. This kind of evidence is a valuable cross-check for the biological data.
Finally, many lakes are located in areas of tectonic activity. The great lakes of east Africa, for instance, sit in deep downdropped basins—grabens—and have uplifted mountains along their banks. Lake Baikal does too. Coring studies of these lake basins shed light on the behavior of the crust as continents break up and come together.
The new discipline of limnogeology combines insights and methods from marine geology, tectonics and traditional limnology. Limnogeologists have an important role in current research into global tectonics and climate change.
Kerry Kelts knew most of this when he dreamed of a drilling program for the world's lakes. He became the prime mover in this effort, coining the name "limnogeology" and heading the Limnological Research Center at the University of Minnesota. His breakthrough came with a new program to collect evidence of global change on the continents, the International Continental Drilling Project or ICDP. The ICDP planners formed a task force for a lake-drilling program, and the work of creating a land-based DSDP gained the momentum it needed.
By 2000 the Global Lake Drilling or GLAD program had designed and built its drilling ship, GLAD800. It's a floating platform that is transported in pieces, using standard shipping containers, and assembled wherever a lake exists. Its hydraulic piston corer and diamond drilling rig can retrieve cores through up to 800 meters of water and sediment. It works just as well on dry land, too—say, on a playa.
GLAD800 was assembled in Great Salt Lake, Utah, for its first drilling project. Kerry Kelts stood on deck as the first hydraulic piston core was raised on 12 August 2000. The next day he flew back to Minnesota to begin treatment for Hodgkin's disease. Less than six months later he was gone. In his honor GLAD800 has been christened R/V Kerry Kelts. Long may it ride the waves.