65-Foot Dune

Picture this if you can: 27,000 years ago, what scientists call the “Laurentide Ice Sheet” covered the entire state of Maine. In fact, it stretched from Canada all the way to Cape Cod. But what exactly does an ice sheet have to do with a landscape like this? First, ice sheets are heavy! Think about how heavy a one-foot cube of ice would be. Do you think you’d be able to lift it? How about 3-feet? Well, this Ice Sheet was over a mile thick! It was so heavy it caused all of the landmass under it to sink.

Glaciers move very slowly, but over thousands of years, they scrape and grind bedrock and boulders, creating different sizes of sediment. So it’s slowly pushing the land down, grinding anything in its path, advancing from Canada through Freeport—down, down, down. But as the temperature on the planet started to warm, it melted back and retreated north. Here in southern coastal Maine, the Ice Sheet was right up against the ocean as it was melting back, and it dumped sediment into the sea.

The ocean waters sorted the sediment into different sizes. A blue-tinted sediment found beneath the dunes was of the finest sand and marine clay that was once sitting at the bottom of the sea floor. When the land finally rebounded and Freeport was no longer under water, these very fine sediments started blowing around and settled in a few different spots. So right now, you’re looking at Maine’s biggest deposit of fine glacial sand and clay from the Laurentide Ice Sheet. Pretty amazing, right?

After dunes were formed around 13,000 years ago, they were gradually covered with topsoil and vegetation. And eventually a forest grew.

The next bit of the tour is at the top of the 65-foot dune, if you’re up for the walk.

If you look out towards those barns, you will see two forests. If Elaine Polackewich was my boss today, she might have me tell you that the forest on the right gave birth to the forest on the left when its seeds and cones fell and blew in that direction. But we now know that they’re both about the same age, and both were the result of reforestation after the original disturbance caused by overfarming. Can you think of a story of how those separate forests came to be? Maybe two trees had a fight and one wanted to get away from the other. Do you think that’s possible?

Let’s go down and get a closer look at that forest on the left. We’ll look at some of the local plants that grow in this strange environment. And then I have a treat for you... I won’t tell you what it is, but it’s very old and you can sit in it!