The Gambia has no migrating wildebeest, giraffes or any of the large animals commonly associated with Africa. However without leaving your hotel you can see a breathtaking variety of bird life, in addition to monkeys and lizards. Baboons and crocodiles can be seen nearby and then far up the river, hippos.
As the gasses collect in the magma chamber, the pressure rises. It is possible for the pressure to rise so much that the chamber cannot contain the magma and it erupts explosively. Some US Parks that have active volcanoes formed as the result of subduction related processes are: 1  Crater Lake National Park, OR.
The formation of volcanoes is a result of the subduction of the oceanic crust. As the oceanic crust gets forced deeper into the Earth the increasing heat and pressure releases trapped water and gases, the combing effect of which is the crust melting to form magma. This magma rises and accumulates in magma chambers which then feeds and creates volcanoes on the overriding continental plate.