When the Land Turned Green

Deep in the wilderness of northern Maine in the mid-1950s, a Harvard PhD student is wading down a mountain stream into a remote valley. He is taking his first steps to map the geology of 300 square miles of Baxter State Park. He soon discovers a series of unusually shaped rock outcrops-part of an unknown geologic formation, hundreds of millions of years old, still mystifying today because of its relative lack of change despite nearby volcanic activity and massive land movement. Wading on, he has another surprise. In a thin layer of black shale beside the stream, he finds a small fossil of a plant.
Little does he know, but a Harvard PhD's discovery of Pertica quadrifaria in the northern Maine wilderness in the mid-1950s will help scientists unlock the details of a major event in the history of our planet-the transition of plants to land, an occurrence that continues to have a critical influence on the Earth's life-supporting processes, including climate.