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Sedimentary Case Study |
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The Blue Mountains, west of Sydney, are a prime area for the study of large-scale and small-scale landforms development on nearly horizontal sedimentary strata. The striking natural features of the area, carved into the plateau and exposed through the action of water erosion, are visited by tourists and bushwalkers in large numbers annually. The Blue Mountains are known for their contrasts between plateau, cliff and valley landscapes, and the famous blue haze, a vapour produced by numerous eucalypt trees. Downward erosion since the original uplift has allowed many layers of the Sydney Basin and older rocks to present segment of the earth history of this region. The uppermost layer consists of olivine basalt remnants, formed from cooling lava between 14-18 m.y. (million years) ago, and now confined to tops of higher peaks of the western Blue Mountains. The oldest rocks, comprising the region's basement, are faulted, folded, intruded and lightly metamorphosed rocks formed from sediments deposited 470-330 m.y. ago. In between the newer basalt and the older layers are the 'blocky' (massively jointed) sandstones and the soft claystones, mudstones and coal measures of the Sydney Basin. The various rock properties and their sequencing, as well as their tectonic history, have combined to influence the present landscape. Other key factors acting upon the landscape have been erosional processes and a geologically significant period of time. For more information on the landform history of the Blue Mountains, visit the four links below.
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