The Wisconsin Glacier covered all of Branchville from 21,000 BC to 13,000 BC, covering the top of Kittatinny Mountain. End moraines exist in Stokes State Forest, another just off Route 565 north of the Skylands Park and one about a mile south of Ross's Corner. An esker was created when the glacier retreated due to climate warming. Many ponds and lakes created. Culver Lake was created at this time, as the drainage became blocked. Branchville is drained by Culver's Lake Creek and Dry brook. Dry Creek starts at the Branchville Reservoir, travels south, enters into Culver's Creek in Branchville and eventually empties into the Paulinskill. There is a chain of hills between Dry Creek and Papakatin Creek. These hills are what separate the Paulinskill River drainage system from that of the Wallkill. The drainage divide is just north of Route 206 and the goes northwest toward Branchville Reservoir. Water near Route 206 or south of Route 206 drains into the Paulinskill. Water north of Route 206 drains into the Wallkill River.