Why was there an Ice Age?
No single event or action caused the Ice Age. Instead, a number of conditions combined, including the following: Large land masses near the poles created a surface upon which thick ice could form. The formation of mountain ranges caused major climatic change by shifting global circulation patterns. Decrease in atmospheric carbon dioxide reduces the insulating effect of the Earth’s atmosphere, resulting in heat loss. Changes in the position of the North Pole and the Earth’s tilt and orbit around the sun affect how much solar radiation it received. The Last Ice Age The last Ice Age, the Wisconsinan, began about 50,000 years ago. As the environment cooled, a large ice sheet formed in the Hudson’s Bay region, and began to spread south. One lobe entered central Iowa and moved as far south as Greene County. Then, as the climate warmed about 30,000 years ago, this lobe “retreated,” or melted. Then as temperatures cooled again, another glacier, the Des Moines Lobe, entered Iowa and pushed down
