What did happen on top of that rocky hill? Terrain, geology, and historical uncertainty at the Battle of Minisink (1779), New York-Pennsylvania

Inners, Jon D. (retired), Pennsylvania Geological Survey, 3240 Schoolhouse Road, Middletown, PA 17057; Osborne, Peter, Minisink Valley Historical Society, P.O. Box 659, Port Jervis, NY 12771; and Moore, William, Department of Geological and Environmental Science, Susquehanna University, Selinsgrove, PA 17870.

On July 22, 1779, …a party of Tories and Indians under the Mohawk Col. Joseph Brant decimated a pursuing force of New Jersey and New York militia in a bloody fight at Minisink Ford in what is now Sullivan County, NY. Though much has been written on the Battle of Minisink [since the first commemorative exercises held in 1822], the events of that horrific day are shrouded in uncertainty. The causes of this historical confusion can largely be traced to conflicting accounts in early recollections, to the poor quality of battleground maps in many subsequent writings, and to the fact that the wilderness site lay neglected for 43 years before the remains of the slain militiamen were recovered.

The Minisink battleground is preserved as a county park near the top of a flat-topped hill 500 feet above an enclosing right-angle bend of the Delaware River opposite Lackawaxen, PA. Bedrock at the site consists of gently north-dipping, planar- and crossbedded sandstones of the Lackawaxen Member of the Late Devonian-age Catskill Formation. The upper east face of the hill, where most of the battle was apparently fought, consists of a series of four topographic steps formed by sandstone ledges 10 to 20 ft high. The orientation of the ledges [and the topographic configuration of the entire hillside are] controlled by subvertical north-south bedrock joints. The ledges step down to the valley of a small spring-fed stream that descends in a southeast direction to the Delaware.

Terrain and geological features that had an impact on the most probable battle scenario were the Minisink ford (localized the action at a strategic Delaware River crossing), the spring-fed ravine (allowed a party of Brant’s men to come up behind the militia early in the action), the bedrock ledges (controlled the later battle lines and gave shelter to the combatants), and “Sentinel Rock” (an isolated residual boulder that, according to tradition, marks the spot where the enemy broke through the militia’s final hilltop position).

[The Battle of Minisink took place two days after Brant’s frontier raid on the settlement of Minisink (present-day Port Jervis, 17 miles to the southeast) and was the “high water mark” of Iroquoian military success in the Revolutionary War. Nine days later, Gen. John Sullivan began his march northward from the Wyoming Valley to destroy Indian strongholds in western New York, a campaign that effectively crippled the military and political power of the Iroquois Confederacy.]

Poster paper presented at the 36 th Annual Meeting of the Northeastern Section Geological Society of America, Burlington, VT, March 13, 2001.


Inners, J. D., Osborne, P., and Moore, W, 2001, What did happen on top of that Rocky Hill? Terrain, geology, and historical uncertainty at the Battle of Minisink (1779), New York- Pennsylvania: Geological Society of America Abstracts with Programs, v. 33, no. 1, p. A66.