Revolutionary War ) Dunderberg was a landmark for British forces during the
American Revolutionary War, as troops moved over a pass to the west of the mountain while marching to
attack Forts Clinton and Montgomery in 1777. In a report to General
William Howe several days after the Oct. 6, 1777 attack, the British commander
Sir Henry Clinton wrote that at daybreak, 2,100 troops disembarked from vessels at Stony Point: The Avant Garde of 500 Regulars & 400 Provincials ... began its March to occupy the Pass of Thunder Hill; this Avant Garde after it had passed that Mountain, was to proceed by a detour of seven Miles round the Hill [Bear Mountain], and Debouchée in the Rear of
Fort Montgomery, while General
Vaughan, with 1200 Men was to continue his March towards Fort Clinton ... Major General Tryon with the Remainder, being the Rear Guard, to leave a Battalion at the Pass of Thunder Hill to open our Communication with the Fleet. Sir Henry's "Pass of Thunder Hill" apparently stood between what is now called Bald Mountain and the Timp, about a mile southwest of the westerly summit of Dunderberg. It lies about a half-mile east of what is now called Timp Pass. The modern 1777 Trail commemorates Sir Henry's route, and was built in 1974–75 as a joint project of the Rockland County Boy Scouts, the Palisades Interstate Park, the Rockland County Cooperative Extension and the New York-New Jersey Trail Conference. The route was determined by Jack Mead of the Trailside Museum at Bear Mountain from British military records and maps drawn by Major
Robert Erskine, Surveyor General of the Continental Army.
Anthony Wayne, in his successful
attack on Stony Point in 1779, used a route that entirely avoids the Dunderberg area, passing nearly two miles to the west of the Timp. A contemporary trail commemorates Wayne's route and is mapped by the New York/New Jersey Trail Conference.
Spiral Railway Corp. In 1889, the Dunderberg Spiral Railway Corporation formed with the goal of building a hotel at the top of Dunderberg. Tourists were to reach the hotel by means of a steam-powered railway. For the descent, the cars would be
powered simply by gravity as the track wound its way back to the base of the mountain, like a
roller coaster, affording scenic views of the Hudson and reaching speeds of up to . Directors of the Dunderberg corporation included Henry J. Mumford, who with his brother H.L. Mumford, operated the former
Mauch Chunk Railroad of similar design as a successful and well-known tourist attraction during the 1870s in what is now
Jim Thorpe, Pennsylvania. The Mauch Chunk Railroad, originally designed for a coal mine, became the inspiration for modern amusement park
roller coasters. Funding for the Dunderberg project ran out in 1891 and the system was never completed; the reasons for the failure remain unclear. One theory holds that the facility was planned as part of the
Columbian Exposition of 1893.
Verplanck's Point (south of
Peekskill on the Hudson) is said to have been considered as a possible location during the planning stage of the Exposition, and it is possible that the funding for the hotel and the railway collapsed after Congress awarded the location to
Chicago instead. Although the theory is persistent, the idea of an exposition such as that proposed being located so distant from a major city and its infrastructure is unlikely, and no clear documentation has been found to support it. Today, ruins and some signs of the Spiral Railway construction are still visible. The graded areas can be accessed from the Ramapo-Dunderberg and the Timp-Torne trails, and became somewhat popular for walking following publication of William Howell's two volumes of hiking diaries called "The Hudson Highlands" in 1933 and 1934, and reprinted by "Walking News" in 1982.
Edison Mine In 1890
Thomas Edison began to establish an
iron mine by acquiring nearly on the north slope of Dunderberg and the base of Bald Mountain. Two years earlier, the inventor had created a method for using
electromagnets to separate and refine iron ore. The remains of Edison's mine lie southeast of Doodletown Reservoir south of the abandoned "Old Turnpike," between the Cornell Mine Trail and the Doodletown Bridle Path. A tailings pile is on the hillside. The land was eventually acquired by the
Palisades Interstate Park Commission on December 31, 1938. Other abandoned iron mines in the immediate vicinity predate Edison's project, and include those on Bald Mountain and West Mountain.
9W roadway construction In 1911 a roadway was constructed near the base of the Dunderberg, a stretch of what became
U.S. Route 9W (which paralleled
U.S. Route 9 on the eastern bank of the Hudson). A wider so-called "upper level" section of 9W was blasted upslope into the side of Dunderberg and opened to traffic in 1931. The new project was compared in the 1930s with
Storm King Highway and the southeastern approach to
Bear Mountain Bridge, two other mountainside highways along the Hudson built in the same era. For the new highway averaged an elevation above the river of between 200 and . The project was undertaken because it reportedly required less excavation and backfilling than that required to widen the lower roadway to four lanes. Funds for the project had been allocated by the state in 1924. Over a period of years the road was temporarily blocked by landslides on a number of occasions. With the opening of the upper level, the lower highway was to be widened to and carry only northbound traffic, while the upper level, also wide, would carry southbound traffic. Today the lower roadway appears on maps as a minor secondary road labeled "Old Route 9W." More than a mile of this route is now called the Jones Point Greenway and is used solely for pedestrian and bicycle traffic. The upper roadway is three lanes and additional blasting has evidently been completed in recent years. ==Cultural references==