Product of the ice age

Would you believe that land masses that are in northern climates today may have been in tropical regions millions of years ago? It is helpful to have evidence indicating that some areas of the world that are now desert landscape were once covered with vegetation during the ice age. Continental glaciers covered the state of Maine during the last ice age and the Gulf of Maine was formed by their retreat. Harold Borns, a professor of geological sciences and member of the University of Maine's Climate Change Institute, explains that glacial ice finally left Maine about 12,000 years ago. As it passed through the state, the massive ice sheet left records of its passing. The enormous glaciers flowed slowly across the state and out into the Gulf of Maine. The ice age provided an environment that is now rich in marine life, like none other in the United States.

Big Rock ridgeThe Big Rock Ridge area displays a series of well-defined moraines formed in the sea as the glacier retreated northwest about 15,300 years ago. The large granite boulders dropped off the front of the glacier. Photo courtesy of: Michael Hermann, and the Maine's Ice Age Trail Down East Project. Borns describes "a time almost 14,000 years ago when ocean waves broke against ice cliffs and rivers poured off the edge of a dying ice sheet, carrying streams thick with sediment into coastal waters.

"There was water to the south and east, and ice to the north," stated Borns. This was the beginning of Maine as we know it today. Everything was locked in ice or under water."

MorrainesAerial view showing several bouldry moraines crossing a blueberry field. The ice margin retreated from right to left (northward). Photo Courtesy of W.B. Thompson, Maine Geological Survey. A specialist in ice age geology and climate change, Borns explained that glaciers always move forward and melt backward. He stated that when there is a balance between melting and forward flow, glaciers act as giant conveyor belts that move rock and gravel embedded within them toward their leading edge, where it is heaped up in ridges.

Ridges of glacial debris called "moraines" formed at the edge of the Laurentide Ice Sheet that once covered Maine. Moraines mark the success of the retreating glaciers. They consist largely of random mixtures of silt, sand, gravel and boulders carried by the glacier and heaped up in ridges along the ice moraine. Moraines can be as large as hundreds of feet across and thousands of feet long. Best seen in open blueberry fields in southern Maine, moraines are abundant along the Ice Age Trail. Some are plainly visible, while others are buried under clay that accumulated on the sea floor.