Geology and Topography

• Geology
• Terrain

Geology

The majority of the province consists of the South East Queensland vegetation bioregion, which is characterised by a variety of geology types.  The Australian Natural Resources Atlas (ANRA, 2002) has more detailed geological descriptions about the various vegetation bioregions composing the SEQ province:

• The South East Queensland vegetation bioregion is characterised by metamorphic and acid to basic volcanic hills and ranges (Beenleigh, D'Aguilar, Gympie, Yarraman Blocks), sediments of the Moreton, Nambour and Maryborough Basins, extensive alluvial valleys and Quaternary coastal deposits including high dunes on the sand islands such as Fraser Island.
• Brigalow Belt South consists of predominantly Jurassic and younger deposits of the Great Artesian Basin and Tertiary deposits with elevated basalt flows.  Sandstone ranges and landscapes of the Barakula and Inglewood sandstones.

Terrain

Relief ratio values for the South-East province range from low to high, with a mean of 0.03. Low relief values are confined to small patches within the province, particularly the coastal and north-western sections of the province. The South-East province has steep relief in the southern sections of the province (foothills of the Great Dividing Range), and to the west of the coast (D’Aguilar, Blackall and Connondale ranges). Stream segment slope values throughout the province also range from low to high, with higher values corresponding to areas with higher relief ratio values.

The province is strongly dominated by erosional flatness index class. Only a small proportion of the province contains valley bottom flat areas (in the areas with low relief ratio), and ridge top flat is almost absent.  This is likely to result in dominance of coarse bed material in South-East streams and implies a dominance of aquatic assemblages preferring coarser substrate types at the province scale. Any biota preferring depositional areas are likely to be restricted in this province. The limited extent of valley bottom flats suggests floodplains and the processes associated with floodplain inundation are not likely to be important to the ecology of South-East rivers. The scarcity of depositional areas in the South-East province is likely to be associated with the relatively low turbidity of the area and subsequently the widespread distribution of submerged macrophytes.

In some sections of the South-East province relief is steep and stream slopes are high. In steeper catchments, run-off is generally faster, producing more peaked discharges and greater erosive power (Thorne, 2004). This contributes to high disturbance intensity of spates in these steeper sections of the province. In other sections of the province, relief is generally shallow and stream slopes are low, contributing to low disturbance intensity of spates in these sections.

Information about terrain

Information about methods

Province Terrain Map   State Terrain Map