Driving east from Far Hills on Liberty Corner Road (before you get to I-287), the land drops off to the right into a deep gorge called Moggy Hollow. This was once, 19,000 to 14,000 years ago, the outlet to Lake Passaic, a 30-mile-long lake, created when the Wisconsin Glacier blocked the area’s natural drainage system. Today, Moggy Hollow Natural Area (adjacent to Leonard J. Buck Garden) in Far Hills is preserved by the Raritan Headwaters Association.
No trails exist into the hollow itself, which is marshy and surrounded by the steep sides of the gorge. Moggy Hollow was selected for inclusion in the National Registry of Natural Landmarks in 1970. The Great Swamp is also a local remnant of Lake Passaic.
The photo below shows the bottom of Moggy Hollow looking northwest up toward Liberty Corner Road.
If memory serves correctly, Moggy Hollow was gifted to the Leonard Buck Gardens by my grandfather, James Malcolm Belcher, Sr. It had been part of the farm, Lo-an-Oak,
Hi Marion, The Belcher family, including J. Malcolm Belcher, donated over 11 acres of land directly to the Raritan Watershed Assoc. (the forerunner of Raritan Headwaters Association) in 1967. The remaining two acres were donated by Leonard Buck in 1968. See: https://www.raritanheadwaters.org/preserves-map-page/moggy-hollow-natural-area/