Complex sentence: There are extensive mangrove swamps at the head of the harbour, and some of the oldest fossils in the North Island, dating to the early Permian about 270 million years ago, are found in the Whangaroa area.
Split into simpler sentences: There are extensive mangrove swamps at the head of the harbour. Some of the oldest fossils in the North Island, dating to the early Permian about 270 million years ago, are found in the Whangaroa area.