8523-37 Moresford - Lucas Point Area
8523 - 33 to 37 - Snowy River Gorge.
This information has been developed from the publications:
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Location: | Snowy River between 134525 and Lucas Point 120470. | |
Abstract: | Exposure of faulted contacts between Buchan Caves Limestone and Snowy River Volcanics, and the fault contact between Ordovician sediments and Snowy River Volcanics, controlled river valley orientation, minor surface karst landforms and an important cave system. | |
Access: | Moresford Road and Old Basin Road. | |
Ownership: | Predominantly Crown land (part Snowy River National Park). | |
Geology: | Snowy River Volcanics composed predominantly of rhyolites and rhyodacites are exposed in the Snowy River Valley between Basin Creek and Moresford. The rhyolites are of particular interest as they display well developed flow banding which is often enhanced by differential weathering of the softer bands. The rhyolites and rhyodacites are highly fractured and are often traversed by veins of calcite and red jasper, which occur singly or together in geodes. In the Moresford area Buchan Caves Limestone is exposed in the Snowy River Valley. This deposit is separated from the surrounding Snowy River Volcanids by a complex series of faults. A particularly good exposure of the Spring Creek Member of the Buchan Caves Limestone occurs in the Snowy River to the north of Moresford. Rhyodacite is exposed in the river bed and this is overlain by agglomerates, mudstone, silicous tuff, weathered tuff, and dolomitic limestone, all of which dip to the west at approximately 15 degrees. Snowy River Volcanics are faulted against Ordovician meta sediments at Lucas Point. The metasediment are schistose, highly contorted and steeply dipping in contrast with the comparatively horizontal bedding of the volcanics. | |
Geomorphology: | Along the Snowy River the more erosion resistant volcanics result in steep valley slopes while the slopes in the areas of limestone outcrop are of lower gradient. The small limestone outcrop at Moresford contains several dolines and a single known cave system. This outflow cave is essentially joint controlled and is of particular significance as it is a maternity site for magaphyllus (Little Horseshoe Bat). The Snowy River has cut an entrenched meander at Lucas Point and this is contrasted with the relatively straight river channel orientation to the north of the point. The change in orientation is related to the Yalmy Fault which bisects the Lucas Point ridge. The alignment of the river here is clearly related to erosion along the fault line or fault dislocation, although the exact nature of this relationship has not been determined. Minor tributaries in this area have cut deeply incised valleys to the local base level of the Snowy River. An excellent example is Raymond Creek which has formed a minor gorge at the head of which is a substantial waterfall. The crest of the waterfall is associated with a change in lithology form volcanics to sediments. | |
Significance: | Regional. The area clearly displays the structural relationship between the major lithologies of the Snowy Valley. Control of landform by different rock types and structures is well illustrated by the Lucas Point meander and the valley form and karst terrain at Moresford. It should be noted however, that the Moresford Cave is probably of national significance as a breeding site for the bat R. megaphyllus. | |
Management: | The significance of the site is dependant on the maintenance of exposures in the Snowy River Valley. The construction of reservoirs would seriously degrade the value of this site. | |
References: | Bradley, K. 1969. 'Geology of the Murrindal River - Yalmy River area east of Buchan, Victoria', Proc. R. Soc. Vict., 85 :277-285. | |
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