One of the key reasons for Federation was to achieve a united defence force which could better protect Australia. Around the 1880s, the Australian colonies had become increasingly concerned over the close proximity of foreign powers.
Split and merge into it. Answered by The Community. Making the world better, one answer at a time. Dissolved gases trapped in the magma provides the force that causes magma to erupt to the surface. Magma is molten material before it reaches the surface and is lava.
Magma chambers are large reservoirs beneath the Earth's crust that hold hot magma. Magma is less dense than the materials that make up the mantle, which causes it to pool below the crust and exert pressure. When the pressure is too great, magma is expelled through the main vent of a volcano.