"on the north by Hook Mountain (a basaltic lava flow) and by a line which roughlybisects the Town of Montville. The western boundary is defined by the trace of the Ramapo Fault and the beginning of the Highlands Physiographic Province. The boundary to the south and the east is formed by the Second Watchung Mountain range, including portions of Union, Essex and Somerset Counties, New Jersey."[1]
This area includes the following municipalities:[1]