Merri Creek Management Committee

Site locationLOCATION: YARRA 5000/04.06 E23750 N14250

Cliffs and bluffs on the left bank of the Yarra river opposite the confluence with Merri Creek.

ACCESS: Yarra Blvd. gives access to the outcrops. Excellent views of the cliffs are obtained from the open space area adjacent to the Merri Creek at Dights Falls.

OWNERSHIP & MUNICIPALITY: Public Land - Yarra Bend Park, managed by Yarra Bend Park Trust. City of Kew.

SITE DESCRIPTION: Sandstones and interbedded mudstones of the Melbourne Formation (previously Dargile Formation) crop out as cliffs and bluffs along the left bank of the Yarra River. Fossils of the genus Monograptusfound in mudstones and fragments of shelly fossils in the sandstones are the basis for determining the age of the beds. The present cliffs are former river bluffs that have been re-activated as the Yarra River was deflected to the south by lava flows pouring down the Merri Creek and Darebin Creek valleys. The cliffs display excellent geological sections of the Silurian rocks showing depositional and tectonic features such as the alternation of strata, well-preserved ripple marks on the upper surface of sandstone beds, anticlines, synclines, faults and joints. Dights Falls is a natural cascade in the Yarra River where it crosses a thick sandstone bed dipping gently to the south east i.e. obliquely across the river. The surface of the falls was raised in the nineteenth century by construction of concrete weir to divert water into a channel as a power source for the flour mill built by John Dight (Hall, 1989). The exposures between Johnston Street and Dights Falls form the core of a geological excursion in the Studley Park area.

SIGNIFICANCE RATING: STATE

The significance rating for this site is very much based on its traditional role as an introductory teaching locality for geologyand geography students from Melbourne, schools, colleges and universities. To generations of geologists trained at these institutions, this is one of the most familiar geological locations in Victoria. It has a number of different geological and geomorphological features that form the basis for an informative and challenging geological excursion. This is the best natural surface exposure of the Silurian sedimentary bedrock of the Melbourne region, and an excellent display of deformed sedimentary strata. The site is on public land, is easily and safely accessible, and is used at all levels of teaching from primary school to university level. Adequate documentation of the features of the site is available, ranging from early geological papers (Hauser, 1923, Nicholls 1930, Hills 1941) to the recent geological excursion guide by Webb (1988). The high significance rating is partly attributed to its history of use, the excellent rock exposure, the range of features and the accessibility of the site in a metropolitan setting.

SENSITIVITY, THREATS, POTENTIAL UTILISATION OF THE SITE.

CLASS 2. Although not strictly part of the Merri Creek catchment, the site is included as the cliffs are related to events in the Merri Creek (i.e. the flows of lava that blocked the Yarra River). Some aspects of the site are best appreciated when viewed from the Merri Creek delta (Photo 1). The site is robust being made of hard rock materials although a certain amount of deterioration has occurred due to pedestrian traffic. A fossil locality in the mudstone has been severely degraded and slumping of weathered sediments above the access track has partly obscured some sites. Numbers painted on some outcrops identifying localities of past excursions should he removed. The site needs some on-going maintenance such as removal of weathered and slumped material along the old track from the Boulevard (although this is outside the area supervised by the Merri Creek management Committee). It is anticipated that the site will continue to be an excursion venue for educational institutions.

REFERENCES:

Hauser, H.B. 1923, The geology of Studley Park. Proc. Pan-Pacific. Sci. Congress. Nicholls, A. 1930, The structural features of the Silurian rocks in the Melbourne District. Proc. Roy. Soc. Vict., 42 Part II, 129-134.

Hills, E.S. 1941, The Silurian rocks of the Studley Park district. Proc. Roy. Soc. Vict., 53 Part I, 167-191.

Bell, G. et al. 1967, Geology of the Melbourne District. Bull. geol. Surv. Vict., 59.

Webb, J.A. 1988, Studley Park and Royal Park, in Clark, I., Cook B. & Cochrane, G.C. (eds.) Victorian Geology Excursion Guide, Aust. Acad. Sci., Canberra.

Hall, R. 1989, Merri Creek parklands, Aboriginal and historical heritage study. Report prepared for the Merri Creek Bicentennial Committee (unpub,)

Dipping beds of sandstone and mudstone of the Melbourne Formation at Dight's Falls

Photograph 1. Dipping beds of sandstone and mudstone of the Melbourne Formation at Dights Falls.


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