The Tweed volcano is a 100 km-wide shield volcano which straddles the coastal NSW-Queensland border and which last erupted 20 million years ago. The central plug of the volcano is Mt Warning : the first place to receive sunlight each morning on the Australian continent. This volcano was once around 2000 m higher than its present eroded surface and during its volcanic history, covered nearly 7000 km2 with lava. Today over 4000 km2 remained covered by lava after erosion. This slide is of a digital elevation image of the Tweed Volcano. This image uses colours to represent heights - red being the highest points and blue being the lowest points. It is easy to recognise the flanks of the volcano as well as the eroded central area and Mt Warning. (Slide : AGSO & AUSLIG)