Southwest oriented North Branch Neshaminy Creek and southwest oriented Pine Run join northeast oriented West Branch Neshaminy Creek at Chalfont to create the meandering and east oriented Neshaminy Creek, which eventually meanders in a southeast, south-southeast, and south direction to join a southwest oriented Delaware River segment. The Chalfont Elbow of Capture is just one of several intriguing elbows of capture found within the Neshaminy Creek drainage basin. These Neshaminy Creek elbows of capture provide important information related to the source of water that eroded the Wissahickon Gorge in northwest Philadelphia, among other regional features.

 

Figure 1: The Chalfont Elbow of Capture is where northeast oriented West Branch Neshaminy Creek joins southwest oriented North Branch Neshaminy Creek and southwest oriented Pine Run to form east oriented Neshaminy Creek, which eventually turns to flow in a southeast and south direction to join a southwest oriented Delaware River segment. Headward erosion of the Neshaminy Creek valley captured the parallel southwest oriented flow channels, which prior to their capture had been supplying water to the newly eroded south oriented Wissahickon Creek valley and the Schuylkill River. Plumstead Hill is located between the two parallel southwest oriented streams. United State Geological Survey map digitally presented using National Geographic TOPO software.

The North Branch Neshaminy Creek and Pine Run drain the southwest ends of southwest-to-northeast oriented through valleys separated by southwest-to-northeast oriented Plumstead Hill. The through valley northeast ends are drained by northeast oriented streams flowing to a southeast oriented Delaware River segment as barbed tributaries. Prior to headward erosion of the deep southeast oriented Delaware River valley the southwest oriented flow eroded the two parallel through valleys with the water coming from a yet to be determined source located north and east of that present day southeast oriented Delaware River valley segment.

 

Figure 2: Reduced size map showing through valleys linking southwest oriented North Branch Neshaminy Creek and Pine Run with northeast oriented streams flowing as barbed tributaries to the southeast oriented Delaware River (in map northeast corner). North Branch Neshaminy Creek flows to the lake at the map southwest corner. Pine Run flows in a southwest direction through Dyerstown (the urban area east of the lake). United States Geological Survey map digitally presented using National Geographic TOPO software.

Prior to Neshaminy Creek valley headward erosion from what was probably an actively eroding southwest oriented Delaware River valley the southwest oriented water flowing in the two parallel through valleys continued to flow in a southwest direction to and across the present day Wissahickon Creek headwaters region. Headward erosion of the Wissahickon Creek valley captured the southwest oriented flow and diverted the water in a south direction through the actively eroding Wissahickon Gorge to what at that time was probably a newly eroded southeast oriented Schuylkill River valley.

Neshaminy Creek headward erosion from what at that time must have been an actively eroding southwest oriented Delaware River valley captured the southwest oriented flow in the two parallel southwest oriented valleys and diverted the captured water in an east, southeast, south-southeast, and south direction to the newly eroded southwest oriented Delaware River valley. When  Neshaminy Creek valley headward erosion captured the southwest oriented flow in the two parallel valleys the southeast oriented Delaware River valley segment to the northeast had yet to be eroded. Following the Neshaminy Creek valley capture of the southwest oriented flow Delaware River valley headward erosion captured the southwest oriented flow channels and beheaded the two parallel flow channels and diverted the water in a southeast, south, and southwest direction along the present day Delaware River route. Flow on northeast ends of the beheaded flow channels was reversed to create what are today northeast oriented streams flowing as barbed tributaries to the southeast oriented Delaware River segment.