Complex sentence: They made their homes in the small grotoes along the river-valley, but when they relized that there were no depoists, they abandoned their settlement and moved to Vila do Topo, on the island of São Jorge.
Split into simpler sentences: They made their homes in the small grotoes along the river-valley. When they relized that there were no depoists, they abandoned the colony, and moved to Vila do Topo, on the island of São Jorge.