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Fort Howe, Saint John

Fort Howe was built during the American Revolution and designated as a National Historic Site in 1929. Today Fort Howe hill is a popular lookout and provides a view of Uptown Saint John and the harbour. Three geologic terranes are also visible from this vantage point:  the Caledonia Terrane, the Brookville Terrane, and the Kingston Terrane.

If you were to stand on Fort Howe, the Brookville Terrane would be beneath your feet. The grey Ashburn Formation, part of the Green Head Group, is a limestone that has been baked under pressure into marble. It is smooth and rounded, worn by glaciers and weathering. These are the oldest rocks in New Brunswick, formed between 1.2 billion and 750 million years ago near the end of Precambrian time. The rock-forming sediments were deposited in an ancient ocean. It contains stromatolite fossils, the layered remains of cyanobacteria that grew in the shallow ocean.