Complex sentence: The northwestern parts of the Shield, located roughly north and west of Sudbury, are known as the Superior Province; this is the largest of the three sections, covering about 70% of the Shield portion in Ontario.
Split into simpler sentences: The northwestern parts of the Shield in Ontario, located roughly north and west of Sudbury is known as the Superior Province. The Superior Province is the largest of the three regions of the Canadian Shield portion founded in Ontario, covering about 70% of the Shield portion in Ontario.