The Hudson Highlands are mountains on both sides of the Hudson River in New York state lying primarily in Putnam County on its east bank and Orange County on its west. They continue somewhat to the south in Westchester County and Rockland County, respectively. North to south they fall between Newburgh Bay and Haverstraw Bay, the latter forming the northern region of the New York - New Jersey Highlands. The Hudson River enters this region in the south at Dunderberg Mountain near Stony Point, and from the north in the vicinity of Breakneck Ridge and Storm King Mountain near Cornwall, New York. These highlands have played a significant role in America's environmental, cultural, and military history. Geology The bedrock of the Highlands is part of the Reading Prong and more than a billion years old, formed during the Grenville Orogeny. It represents the very core of the Appalachian range, which has been formed by successive mountain-building events (orogenies). The present mountains have been exposed by the process of isostasy through the late Cenozoic Era. The hills were given their rounded form when glaciers cut through the Appalachian Mountains here. The Highlands are among the lowest summits in that range, and the Appalachian Trail reaches its lowest elevation in the Trailside Zoo between Bear Mountain State Park and Bear Mountain Bridge. Conversely, the river becomes narrower and deeper through the Highlands, reaching its deepest point of 216 feet (66 m), near Garrison. Many stretches are challenging to navigate, earning nicknames like "World's End." History Prior to European exploration, the Hudson Highlands were inhabited by Native American Lenape people. Henry Hudson and his crew on the Half Moon were the first Europeans known to see the Highlands when they explored the river in 1609. The mountains became strategically important during the American Revolutionary War, when it was important for the Continental Army to hold the river valley and prevent the British from cutting New England off from the rest of the colonies. During the Revolutionary War, to prevent British shipping from using the river, the Hudson River Chain was forged at the Sterling Iron Works in Warwick, New York, a town in Orange County. From 1778 to 1782, the chain was stretched across the river from the Fort Clinton at West Point. The site of the fort is today the easternmost point of the grounds of the United States Military Academy. The