Unlike most suburban towns whose names have little or nothing to do with reality, Glen Rock was actually settled around an enormous rock left by retreating glaciers in a small valley (glen).
"Glen Rock is named for a 570-ton boulder, deposited by a recent glacier, that stands near Rock Road, the town's main street. The rock had been called Pamachapura, or Stone from Heaven, by the Delaware (Lenape) Indians, it served as a base for Indian signal fires and later as a trail marker for colonists."
