he Chickahominy River is a Coastal Plain tributary to the James River that heads northwest of Richmond in the Fall Zone. For its first 15 kilometers the Chickahominy flows over igneous and metamorphic bedrock of the Piedmont, but soon becomes a Coastal Plain stream near Mechanicsville. The low-gradient Chickahominy sluggishly flows through broad swampy lowlands for 60 kilometers from Henrico County to eastern New Kent County. 10 kilometers southeast of Province Forge the Chickahominy River becomes an estuary and makes a turn towards to the south.
When sea level was higher during warmer (non-glacial) periods in the Pleistocene the Chickahominy was a much broader river. The ancient riverbanks and meander loops are still recognizable. As sea level rose after the last glacial interval (during the last 20,000 years) the Chickahominy has also risen causing old flood plains and valleys to be backfilled as marshes.