Sill. In this respect, Prospect Hill likely marks another location where the Palisades magma found a way to the surface, albeit not as significant as in the Ladentown Outlier. Sand Brook Outlier The Sand Brook Outlier, located in the eastern part of Delaware Township, New Jersey, appears nearly identical in construction to the New Germantown Outlier. A low ridge composed of Orange Mountain Basalt forms a horseshoe around the eastern edge of a belt of sedimentary strata from the Feltville Formation. In the middle of the outlier is a dome-like structure of what is likely Preakness Mountain Basalt, not unlike Round Top in the New Germantown complex. The thickness of the basalt in this outlier is estimated at nearly 400 ft (~120 m), similar to New Germantown. Jacksonwald Outlier The Jacksonwald Outlier is the only Watchung Outlier in Pennsylvania. It is located over 100 km southwest of the actual Watchung Mountains in Exeter Township. The outlier shares some similarity with the Sand Brook and New Germantown outliers. As in the other two outliers, the Jacksonwald Outlier features a low, horseshoe shaped ridge of Orange Mountain Basalt (sometimes referred to as just the Jacksonwald Basalt) that embraces an area composed of sedimentary strata from the Feltville Formation. However, unlike in the Sand Brook and New Germantown outliers, the Jacksonwald Outlier lacks a central dome of Preakness Mountain Basalt. The thickness of the basalt in this outlier is estimated to be in excess of 325 ft (~100 m). An interesting trait of the Jacksonwald Outlier is that it is surrounded by a ridge of intrusive diabase on its eastern side. The diabase, which lies stratagraphically below the basalt, is thought to have been intruded into the syncline containing the Jacksonwald Outlier during or after some degree of folding had affected local strata. The diabase is therefore considered to constitute a phacolith. See also Watchung Mountains References External links Geocaching.com – Two Hundred Million Year-Old Lava Flow! Earthcache at the base of Prospect Hill described by the New Jersey Geological Survey. Triassic volcanism Jurassic volcanism Volcanism of New Jersey Volcanism of New York (state) Volcanism of Pennsylvania Watchung Mountains Mountains of New Jersey Ridges of New Jersey Mountain ranges of New Jersey Mountains of Pennsylvania Mountains of New York (state)