The park is appropriately named. The rocks found in Rockwood Park are quite diverse. They include Precambrian marble, Precambrian gneiss, Precambrian to Cambrian igneous rocks (granite), tonalite, granodiorite and dacite and Devonian sandstone and conglomerate. Two geologic terranes are found in the park. The Caledonian Terrane includes the McBrien Lake Formation dacite and the Cambrian Saint John Group, found just outside the park. Northwest of the dacite, rocks belong to the Brookville Terrane. The Devonian rocks are a later cover sequence of younger sedimentary rocks.
A major fault called the Caledonia Fault separates the terranes. The main road past the Lily Lake Pavilion follows the fault line.
A Long History
Rockwood Park has had a long history of scientific study and geological exploration. The Natural History Society of New Brunswick examined the geology of the park in the late 1800s. Rock specimens Society members collected from the park are found in the New Brunswick Museum collection. Howes Cave in the Ashburn Formation marble was discovered in the 1860s and described in the Society Bulletin in 1904. Even earlier in the 1800s a graphite mine operated near the outlet of Lily Lake.
Rockwood Park has many trails that allow opportunities to explore the geology on foot, on a mountain bike, or on horseback. Get up-close by rock climbing with a guide. In the winter it is a great place to explore on cross-county skis or snowshoes.