July 20, 2010

Cape Cod National Seashore, Massachusetts

Program note: The Mount Rainier National Park posts should begin tomorrow

Cape Cod may be the playground for the rich and famous of New England, but it is also a fascinating geological and ecological feature. This long hook-shaped peninsula is the terminal moraine of the great Ice Age glaciers that covered the region. Along with Martha's Vineyard, Nantucket, and the other associated islands, Cape Cod represents all the sand and sediment that was plowed and pushed south and then deposited at the edge of this mass of ice.

One of the only places to get a real birdseye view of the cape is from the Provincetown Tower out at the end of the peninsula. This 250 foot tower is dedicated to the Pilgrims who landed here first and signed the Mayflower Compact before heading to Plymouth. It gives panoramic views of the cape and the bay.

Marconi's Radio Station, built in 1902, was key to radio transmissions with ships in the Atlantic in the early era of radio.

In addition to the geologic features, Cape Cod National Seashore also protects a variety of interest ecosystems. Much of the landscape is sand and represent some of the best preserved coastal ecosystems in the Northeast.

Throughout the sand dunes of Cape Cod, coastal cranberry bogs are found in the recessions between the dunes that collect the water that drains through the porous sands. They are pretty tasty, if not a bit sour.

The dunes have different vegetation types based on how stable the sands are and how much moisture collects. Because sand can drain water so easily, it can be almost desert-like conditions for plants, despite heavy rainfall. The highest and loosest materials tend to only support grasses. But, in the basins and in areas protected from wind, shrubs and even trees eke out a living.

Some stunted pitch pines eking out a living in the dunes

Throughout Cape Cod there are kettle lakes. These lakes formed when chunks of ice, left behind by the glaciers, were buried by sediment as the glaciers retreated. As they slowly melted over hundreds of years, they left depressions filled with melt water. Some lakes remain open water, while others have been slowly filling in with sand and sediment to form marshes, bogs, and swamps.

Here you can see the edges of a kettle lake where the silt, mud, and decaying vegetation have been filling in the depression for centuries. As it does, the lake forms a marsh and then eventually a bog.

In places where the old kettle lakes have filled completely in with sediment and peat moss, Atlantic white cedar swamps have formed. Walking on the moss, it is a spongy, not quite solid surface. The roots of the cedar trees provide a base structure to this wetland.

As the bogs and swamps further solidify, the soils develop and become more well drained, deciduous hardwood trees such as beech, elm, and maple, as well as, pines and oaks will behind to crept into the cedar swamps.

Where the soils are most developed, American Beech and other northern hardwoods dominate

Here a warbler sites in a pitch pine stand on well-drained sandy soils

Another ecosystem found on the cape are salt marshes. When sea level was much lower, freshwater streams flowed to the sea. As they eroded into the sandy sediments they formed depressed valleys. As sea level rose, the waters flooded these valleys to form these marshes. They are brackish as the freshwater streams mix with the invading ocean waters. They tend to be dominated by salt-tolerant grasses and are rich in crustaceans, shorebirds, and other wildlife.

Originally, of course, Cape Cod was a peninsula. But, it was hazardous for ships coming from the south toward Boston to go out into the open ocean and around the hook. So, they carved out the Cape Cod canal to allow ship traffic to get into the more sheltered Cape Cod Bay. So, technically today Cape Cod is an island.

A red squirrel hanging out on the railing near a marsh

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