Cell Descriptions - South East Natural Resources Management Board

SE3 – Cape Douglas
Landforms
This is a variable cell, with Gambier Limestone and calcarenite cliffs, huge shore platforms, reefs,
and small embayments, dunes and coastal wetlands as notable features. At Umpherstone Bay
there is a narrow coarse sand and flint cobble beach behind platforms and reefs; some beach
ridges are cobbles, with sand capping; and towards Blanche Bay and Middle Point beaches are in
places made up entirely of cobbles. Sand storage in dunes is low in volume: it appears that reefs
have reduced Holocene transgressive onshore sand transport.
At Middle Point the cobble beach is sheltered from heavy offshore surf by wide limestone reefs.
The beach ridge system at Blanche Bay is well vegetated and relatively stable, compared with
further NW. There is a distinctive cobble cuspate foreland immediately NW of Middle Point
(pictured below, centre), that has accumulated on a shore platform; another is found on the SE
side of the headland. These forelands are an unusual landform in South Australia (cf. Pine Point,
York Peninsula), and appear to result from reef refraction of inshore waves, constructing cobble
berms parallel to the two shores of the foreland, in a context of low to moderate wave energy and
plentiful supply of cobble-sized debris.
From Finger Point to Cape Douglas the narrow dunes and cobble ridges are backed by coastal
swamps. Near Cape Northumberland stranded cliff top dune over aeolianite is found. Douglas
Point shows calcarenite cliffs with large shore platforms, also small high tide pocket beaches of
coarse sands and shingle.
Middle Point foreland, Umpherstone Bay beach, dunes and cobble ridges; Middle Point Wetland.
Photograph Coast Protection Board 2008.
Benthic Habitat
Entirely heavy limestone reef inshore, with low platform reef beyond about 1 km offshore.
Seagrass meadows in protected embayments.
Biota
There are 11 flora survey sites, 2 opportune flora sites, 15 Herbarium record sites, 3 fauna survey
sites, and 27 opportune fauna survey sites. There is 429ha of remnant vegetation., which is 58%
of the cell area.
Limestone Coast and Coorong Coastal Action Plan 240