Complex sentence: The Pachaug-Great Meadow Swamp portion of the park was declared a National Natural Landmark in May 1973 due to its Atlantic white cedar swamp.
Split into simpler sentences: The Pachaug-Great Meadow Swamp portion of the park was declared a National Natural Landmark in May 1973. The Great Meadow section of the park is a National Natural Landmark due to its Atlantic white cedar swamp.