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.
When magma erupts from a volcano at the earthâs surface, it is referred to as lava. Igneous rocks are divided into intrusive rocks (or plutonic rocks), which form underground when magma cools beneath the surface, and extrusive rocks (or volcanic rocks), which form at the earthâs surface from lava flows.hen magma erupts from a volcano at the earthâs surface, it is referred to as lava. Igneous rocks are divided into intrusive rocks (or plutonic rocks), which form underground when magma cools beneath the surface, and extrusive rocks (or volcanic rocks), which form at the earthâs surface from lava flows.