The Ice Age played an important role in creating the Dunes. Many years ago, as the Laurentide Ice Sheet (a large glacier) was melting, it moved from the the south and west over Indiana and the present time Dunes area. At the furthest end, this glacier deposited large amounts of clay, gravel and dirt, creating the Valparaiso Moraine. As the glacier melted, the moraine slowed down the movement of water and the flooding eventually led to the creation of many areas of bog and marsh. One of these bogs is Pinhook Bog in the Dunes National Lakeshore. The glacier also brought some trees and plants that you would normally find in southern climates of the United States. For instance, Bear Berries and Prickly Pear Cacti, but much more importantly, the glacier brought the Jack Pine to the area, which is now playing a role in Succession. The glacier also left behind something which is of most importance to the Indiana Dunes and much of Indiana, Illinois and Michigan, Lake Michigan, formerly Ancient Lake Chicago. The Ancient Lake Chicago was much larger than the present day Lake Michigan. What happened was the Dunes were at this lake front and grew just naturally, following all the steps of Succession, and followed the lake, leaving behind climax forest and proceeding further north with the lakeshore. This is why the area of Northwest Indiana is heavily populated with Oak, Jack Pine, and Cottonwood trees. The shoreline of Lake Michigan continues to recede and the Dunes are following this movement. The picture seen to the left here demonstrates how plants and trees like the Bear Berries and Jack Pines were brought to the area of the Dunes. The constant build up of snow compressed the lower layers creating ice, but eventually this pressure became too much and the Glacier moved out in all directions. At some point when the Glacier was further north, it picked up some Jack Pines and other plants and the glacier continued to move further south, carrying these plants.