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.
1)Inside a volcano, pressure builds.The pressure pushes MAGMA upward. 2)Magma pushes toward Earth's SURFACE through CRACKS. 3)Hot LAVA, gases, and ROCK flow from the volcano. 4)Lava COOLS, hardens, and becomes part of the LAND. volcano erupts when pressure pushes molten rock up through cracks in Earth's crust onto the surface.Volcanoes change Earth's surface. a)Molten rock pushes up through cracks in Earth's crust. b)An explosion of ash, lava and magma.