The Sourlands is a region in the U.S. state of New Jersey that includes portions of Hunterdon County, Mercer County and Somerset County. It is centered on Sourland Mountain and comprises parts of Lambertville, East Amwell, West Amwell, Hillsborough, Hopewell Boro, Hopewell Township, Montgomery. The region is flanked by the Hopewell Fault to the south and Amwell Valley to the north that runs from Mount Airy to an area just west of Flagtown and a diabase formation running from Lambertville to Mount Airy. The Sourland also include a hilly area towards the southwest called Pleasant Valley, with a number of farms. Although much of the Sourlands is not conducive to farming, Pleasant Valley and the slopes on the surrounding ridges have a number of farms.