The mixture of peoples and cultures in South America are predominantly descendants of South Americans, native Indians, European colonials and African slave laborers. After the original Spanish conquerors, successive waves of ethnic Europeans tended to settle in particular regions; for example, Italians in Argentina; Germans and Swiss in Southern Brazil. The dominant European Catholicism is blended with elements of West African religious ritual. The climate and terrain are enormously varied and allow for the production of correspondingly varied products. Economic development has created many major modern cities, but at the expense of grave environmental problems.