Final answer:
The New Jersey Highlands, part of the Appalachian Mountains, consist mainly of intrusive igneous and medium to high-grade metamorphic rocks, and are located between the Valley and Ridge Province and the Newark Basin.
Step-by-step explanation:
The mountain range in New Jersey is referred to as the New Jersey Highlands, which is part of the Appalachian Mountains. These highlands are situated between the Valley and Ridge Province and the Newark Basin. The NJ Highlands mainly consist of two types of rocks: metamorphic and igneous rocks. The igneous rocks found here are primarily intrusive, such as granites. The metamorphic rocks are primarily of medium to high grade, with significant geological formations such as the Mount Even Granite and the Hornblende granite of the Byram Intrusive Suite indicating their age and complexity. Despite the Alleghenian Orogeny being a significant event in the geological history of the Appalachian region, evidence of this orogeny in New Jersey has been eroded away. However, the faulting and folding seen in the NJ Highlands and the Valley and Ridge Province are largely a result of this orogeny.