8622 (part 8522) 7-14 Snowy River Estuary and Flood Plain

This information has been developed from the publications:

Sites of Geological and Geomorphological Significance in Central Gippsland (1981) by Neville Rosengren, M.S McRae-Williams and S.M Kraemers.
Sites of Geological and Geomorphological Significance in the Gippsland Lakes Catchment (1984) by Neville Rosengren.
Sites of Geological and Geomorphological Significance in East Gippsland, Victoria (1981) by Neville Rosengren, M.S McRae-Williams

Geological heritage sites, including sites of geomorphological interest and volcanic heritage sites, are under regular revision by the Geological Society of Australia, especially in the assessment of significance and values. Reference should be made to the most recent reports. See the Earth Science Heritage section of the Geological Society of Australia website for details of geological heritage reports, and a bibliography.

Introduction:

The snowy is the largest river in Gippsland in terms of both catchment area and discharge, and the valley south of Orbost includes a number of features of considerable geological and geomorphological interest. The valley here is well defined with distinct valley-side bluffs cut in Miocene and Pliocene limestones and non-marine sediments. A small inlier of recrystallized granite outcrops in the bluff east of Lake Curlip.

The snowy River Valley was incised during Pleistocene stages of lower sea level and during the Holocene marine transgression was flooded by the sea to forma deep and broad estuary. Unlike Lake Tyers and other smaller estuaries to the east which retain the drowned valley configuration, the Snowy River Estuary has been largely filled by alluvial plain with well developed flood plain features such as leave banks, flood crevasse splays, point bars, abandoned river meanders, back swamps and lagoons.

Below the confluence of the Brodribb River the channel form is complex as the Snowy is subject to tidal inflow and there is a large estuarine lagoon – Lake Corringle – to the west. The entrance to the sea is constricted by a long sand spit, an extension of the sand barrier that encloses Ewing Marsh, eastward from Lake Tyres. During recorded history, the entrance has occupied a position varying from directly opposite Marlo to a point almost eight kilometres to the east near Point Ricardo. Only rarely is the entrance completely closed by sand spits. Because of the variable discharge of the Snowy and the incidence of large floods rapid changes occur in the configuration of the entrance and the lagoons at the Snowy mouth.

The swampy and low sandy plain west of Marlo and south of Lake Corringle contains several features that indicate the river once discharges well to the west of its present outlet. This outlet has been long abandoned however, and is enclosed by a sand barrier now surmounted by high vegetated dunes.

The area is a very important site for the study of Late Tertiary sediments as well as the geomorphology, stratigraphy and hydrology of the flood plain and estuarine sectors.

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