Appendix 2 - Vegetation Communities and Regional Ecosystems

Zone classification more robust. Thin surficial layers of alluvial sediment and fine silica sand are
present on some coastal plains on the inner islands although these are generally extremely
shallow with the majority of the fringing coastal plain being influenced by alluvial process which
is continuing in the present geomorphic regime.
5.1.5 Land Zone 7
A minor area of mapped as Land Zone 7 (geol. prefix T) underlies the settlement on Saibai
Island, forming the most topographically elevated portion of the island. This landform is
currently undergoing significant landward erosion through undercutting and collapse of the iron
cemented hard-pan layer, most actively during the summer periods where northerly trade winds
prevail. The inclusion of this feature under the classification of Land Zone 7 is based on the
lateritic exposure evident on the coastline, directed under advice from the Queensland Herbarium,
and has not been validated through formalised soil profiles or geomorphic analysis. Due to the
long history of settlement, this landform is largely devoid of remnant vegetation.
5.1.6 Land Zone 8
Photograph 7. Slabby exposure of
lateritic duricrust on the coastal
fringe of Saibai township.
Land Zone 8 poses few problems for classification, being restricted to the eastern group of islands
including Mer, Erub and Ugar. Landforms associated with Land Zone 8, which include
Pleistocene flow basalts and associated volcanic ejecta, have been adequately characterised in the
introductory sections of this report (Section 1.1.3) and require little expansion in this section.
Basaltic terraces and pavements subject to tidal inundation, supporting mangrove communities in
some locations have been classified as Land Zone 1.
5.1.7 Land Zone 12
Land zone 12 occupies a considerable proportion of the combined island mass, and as previously
described in Section 1.1.3 (i.e. Islands Formed on Acidic Volcanic and Plutonic Basement),
extends through all island groupings with the exception of the eastern group. This is a relatively
simple group to define, including all igneous and volcanic rocks greater than Cainozoic in age,
and as such extends to all basement outcrop in the Torres Strait Islands other than Pleistocene
basalt. There is however significant chemical and structural variation within the grouping and in
3d Environmental – Torres Strait Regional Ecosystem Mapping Project – August 2008
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