Complex sentence: Pierre Melanson and the Acadians who joined him in Grand-Pré built dykes to hold back the tides along the Minas Basin, creating rich pastures for their animals and fertile fields for their crops.
Split into simpler sentences: Pierre Melanson and the Acadians who joined him in Grand-Pré built dykes there to hold back the tides along the Minas Basin. They created rich pastures for their animals and fertile fields for their crops.