Complex sentence: It is rich in natural resources on which many generations have depended for their livelihoods; resources that have not only sustained a growing economy, but have contributed greatly to the culture and heritage that define Mississippi Gulf Coast natives as a people.
Split into simpler sentences: It is rich in natural resources on which many generations have depended for their livelihoods. Resources that have not only sustained a growing economy, but have contributed greatly to the culture and heritage that define Mississippi Gulf Coast natives as a people.