Figure 1: Buckingham Mountain region in Bucks County, PA. United States Geological Survey topographic map digitally presented using National Geographic TOPO software.
Buckingham Mountain in Bucks County is a high southwest-to-northeast oriented ridge (more than 500 feet at its highest point while surrounding landscape elevations are in the 200-300 foot range). According to the Pennsylvania Geological Survey web applications map Buckingham Mountain is composed of quartzite and sandstone of Cambrian age while bedrock south and east of Buckingham Mountain is composed of mudstone, shale, and siltstone of Triassic age and the bedrock north and west of Buckingham Mountain is composed of Cambrian dolomite and calcareous shale. The quartzite and sandstone is much more resistant to erosion than the surrounding bedrock and for that reason remained as erosion stripped 200-300 feet of bedrock from the surrounding region. All rocks exposed in the Buckingham Mountain region have been tilted and uplifted since their formation, although erosion events that removed the 200-300 of bedrock material surrounding the quartzite and sandstone ridge occurred much later in geologic history.
The present day landscape was shaped during an erosion event that began with a regional surface at least as high or higher than the highest points on Buckingham Mountain today. At that time the south oriented Delaware River valley located east of figure 1 did not exist and massive and prolonged southwest oriented floods were moving across the entire region. The flood flow direction was probably shaped as floodwaters eroded shallow channels into the underlying bedrock in which southwest-to-northeast oriented structures are common throughout southeast Pennsylvania. Floodwaters were flowing in complexes of shallow anastomosing channels (diverging and converging channels) with water also moving freely between the channels. These southwest oriented floodwaters were responsible for lowering the landscape on either side of Buckingham Mountain.
Floodwaters were first captured by headward erosion of the deep southeast and south oriented Neshaminy Creek valley (not seen in figure 1). The Neshaminy Creek valley eroded headward from what at that time was the actively eroding southwest oriented Delaware River valley located south of figure 1 and was able to capture the southwest oriented flood flow before the Delaware River valley eroded headward in a north direction in the region east of figure 1. Southwest oriented flood flow moving to the newly eroded Neshaminy Creek valley eroded deep and broad channels on either side of the erosion resistant Buckingham Mountain quartzite and sandstone ridge while the south oriented Mill Creek valley eroded headward across what is today the Buckingham Valley water gap between Buckingham Mountain and Little Buckingham Mountain (an extension of the quartzite and sandstone ridge located just south and east of figure 1).
Delaware River valley headward erosion east of figure 1 first beheaded flood flow channels on the southeast side of Buckingham Mountain and those beheaded flood flow channels reversed direction to flow in northeast directions (with jogs to the southeast) to reach the much deeper Delaware River valley and to create what is today the Pidcock Creek drainage basin (see Pidcock Creek drainage basin entry on this website for detailed discussion). The reversed flood flow in the newly created northeast oriented Pidcock Creek drainage basin captured southwest oriented flood flow moving along the Buckingham Mountain northwest flank. Evidence for that capture is seen in the southwest and south oriented Pidcock Creek tributary originating near Five Points (at the Buckingham Mountain northeast end). Captured flood water from north and west of Buckingham Mountain helped erode the northeast oriented Pidcock Creek drainage basin. Headward erosion of the deep south-oriented Delaware River valley (north and east of figure 1) next beheaded flood flow channels located to the northwest of Buckingham Mountain and Buckingham Mountain region drainage routes and landforms have not been significantly changed since that time.