Optional Enrichment Article

Dr. Richard B. Alley: People who get their water from wells and who live near the coast, or in some other places, have to worry that if they pump too much water out of the ground they will start to get salt water into their wells and they won't be able to use that. These diagrams are from an old publication of the United States Geological Survey but the problem is still new, it's still with us. So here's a diagram that could be Cape Cod. It is of an island from this report, and there is fresh water in the ground as shown there. But it's sitting on top of salty water and there's a little zone of mixing between the two but it's not very thick. So it is possible for a well to pump up fresh water that people can use. The problem is if you pump too much and the water table drops by one foot, the level of the salt comes up by 40 feet and that can get into trouble. So here's a diagram. Start with a water well that is in fresh water at the bottom, where it's pumping from, this is before it starts pumping. When it starts pumping it will lower the water table at the top and that will raise the level of the salt water at the bottom. If it pumps too much then you raise the salt up until it hits the bottom of the well what comes out is saltwater and it's no longer useful to the people.

Dr. Richard B. Alley: A beautiful, natural morning at the beach. But if you turn to the sea, you can see that the evening revelers were there. I've been to the beaches in Greenland. I've been to the beaches of Antarctica, and everywhere I've been, the flotsam and jetsam of humanity are on the beach.

Oceanographers have traced the currents of the Pacific using shoes and rubber ducks that fell off of ships during storms. More importantly, we've probably taken 90% of the big fish out of the ocean. We don't know what an ocean ecosystem should look like because it isn't natural anymore. We've changed everything. We've put so much fertilizer into the ocean from runoff from farming and sewers and other pollution that they cause huge blooms of algae and when they die, they rot and they kill the life around them and make dead zones. Taking care of the ocean is a big deal. And it's a deal we need.

Dr. Richard B. Alley: Beautiful morning for a paddle. The tide's coming in, and a really happy professor is going out to see who's running around in the salt marsh, the Nossett Marsh in Eastham on Cape Cod. This is a place for birding. This is a place for shelling. These sandpipers are out getting breakfast.

Salt marshes are remarkably productive places. They are the nurseries of the fish and the shellfish. They're the nurseries of the ocean. They, too, need care.

The outer beach is coming in as the ocean rises. But the inner side is often hardened by humans and not allowed to move. And if we're not careful, we won't have these nurseries.

Dr. Richard B. Alley: We're on the outer beach at Cape Cod at Nauset, and we're looking at where the ocean has been cutting back a little bit of the bluffs to reveal what's behind. Now, most of the Cape is sand and gravel. It's outwash from the glaciers from the Ice Age. But what we see here is the filling of a lake. A block of ice fell off the glacier, was buried in sand and gravel, and then melted out to leave a little spot, a lake, which is filled with peat that you see here. The peat is the remains of dead plants. And if you look very carefully, you will see within the peat many of the dead plants.

On top here are grasses of the modern world, but they are not down in the material. Lakes die. They fill with this stuff. When you see a lake on the landscape, you should ask yourself, why is this here? Because something recent has happened to make the lake.