how was the galapagos islands formed
The most likely scenario is that the Galapagos are the result of a volcanic hotspot. This is an underground (also underwater in this case) volcano, the source of which remains stationary while tectonic plates move over it. When it erupts with enough force and enough magma, it builds an island. Lesser eruptions make seamounts. As the tectonic plate moves, the island moves off the hotspot.