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.
As for your question, the above should answer that, if a volcano does not erupt and thus empty a magma chamber for what-ever reason, the magma will crystallise and can form a granite (or other intrusive rocks, dependent on the chemical composition of the magma). Due to convergent plates putting more pressure on the mantle, magma will migrate upwards.