“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Cambridge in Dorchester County, Maryland — The American Northeast (Mid-Atlantic)

Choptank River's Natural History

Melting Glaciers created the Chesapeake Bay

Choptank River's Natural History Marker image. Click for full size.
By Craig Swain, June 14, 2008
1. Choptank River's Natural History Marker
Inscription. The Chesapeake Bay was once the extended valley of the Susquehanna River, which flowed directly into the ocean near the mouth of the bay. The Bay and all its tributaries were once non-tidal freshwater rivers flowing through valleys in the last ice age 15,000 years ago when sea level was more than 300 feet below the present level. As the climate warmed and glaciers melted, sea level rose and the Susquehanna Valley and other tributaries like the Choptank flooded with mixtures of freshwater and seawater.

Such flooded valleys are called estuaries where ocean salt water mixes with fresh river water producing some of the most biologically rich habitat in the world. Indeed, the Chesapeake Bay has been called an immense protein factory churning up nutrients to microscopic life that feeds the oysters and crabs, which then feed the fishes and other animals, including humans, that benifit from the ever-changing intermixing of fresh and ocean waters.

Seasonal changes in the Chesapeake Bay bring infusions of fresh water and nutrients from the rivers that flow into the Bay. Summer increases evaporation and reduces river flow, making the Bay saltier. In the fall the rich-waters stay warmer far longer providing food and refuge for migratory birds. Some birds, the Mallard Duck and Great Blue Heron, live along the river all year long. But
Coptank River Overlook image. Click for full size.
By Craig Swain
2. Coptank River Overlook
many birds, especially the waterfowl, pass by as they migrate each winter to the south and each summer to the north. Examples include the Canada Goose, Canvasback Duck, and Lesser Scaup. Osprey migrate each winter as far south as South America.
Location. 38° 34.293′ N, 76° 3.817′ W. Marker is in Cambridge, Maryland, in Dorchester County. Marker is at the intersection of Rose Hill Place and Radiance Drive, on the right when traveling north on Rose Hill Place. Click for map. Marker at the Dorchester County Visitor Center in Sailwinds Park, which can be seen when entering Cambridge from the Choptank River bridge (US 50). Marker is at or near this postal address: 2 Rose Hill Place, Cambridge MD 21613, United States of America.
Other nearby markers. At least 8 other markers are within walking distance of this marker. Choptank River Bridge (here, next to this marker); A Landscape and Lifestyle Defined by Water (a few steps from this marker); Living off the Land (a few steps from this marker); Exploring Dorchester's Fragile Beauty (within shouting distance of this marker); Maryland's Eastern Shore (within shouting distance of this marker); Cambridge (within shouting distance of this marker); Discover: Dorchester (within shouting distance of this marker); Enjoy Our Park (within shouting distance of this marker). Click for a list of all markers in Cambridge.
More about this marker. On the lower left of the marker is a waterfowl migration calendar. On the lower right is a satellite photograph of the Eastern Shore area.
Categories. Natural Features
Credits. This page originally submitted on , by Craig Swain of Leesburg, Virginia. This page has been viewed 1,690 times since then and 22 times this year. Photos:   1, 2. submitted on , by Craig Swain of Leesburg, Virginia. This page was last revised on June 16, 2016.
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