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.
The theory is that pressure and other factors in the gas cause some upward pressure. Magma is formed when the earthâs upper crust melts (for some bizarre reason itâs magma under the earth and lava above). The magma falls down with gravity and is pushed up with the pressure of the gases.