Although the river dates back some 60 million years, the river we see today was shaped during the last Ice Age. About 16,000 years ago, a massive ice field gouged the riverbed to a depth below sea level, thus allowing water from the Atlantic Ocean to enter the Hudson.
For 150 miles, from Manhattan to Troy, the Hudson rises and falls to the flow of ocean tides. The river reverses its direction of flow through tidal changes. Algonquian-speaking Mohican people named the river Muhheakantuck (Muh-HEE-kan-tuck), meaning "river that flows both ways."
An Arm of the SeaThe river's salty seawater is diluted by fresh water flowing from the Adirondack Mountains, the Catskill Mountains, and the rest of its watershed. The leading edge of diluted seawater, called the salt front, frequently pushes north to Newburgh and sometimes to Poughkeepsie during droughts. The meeting of salt and fresh water makes the Hudson an estuary. The river is home to a great variety of fresh and saltwater creatures, such as striped bass, blue crabs and sturgeon.
(photo captions:) · Bald Eagle · Blue Crabs · Peregrine Falcon · Striped Bass · Atlantic Sturgeon