2 The story of Granite and Bega Cheese - Sapphire Coast

The grassland on the Cobargo Granite stands out as it has been cleared of native
forest to expose fertile soils well suited to pasture and dairy farming. The area
producing prime cheese coincides with the geology map.
The Ordovician sedimentary rocks form elevated, erosion-resistant ridges where they
abut the granite. Hot, molten granites intruded into the Ordovician rocks deep in the
crust, cooking them in the process, resulting in a band of hard heat-altered rock
against the granite. Erosion and weathering over millions of years has left the
contact zone standing out as rugged ridges, while the granite has washed away or
formed deep soils.
Just to the south of the Cobargo Granites is Mumbulla Mountain, composed of a
quite different granite type. This is far more resistant to erosion and stands out as a
rugged range above the adjacent Cobargo granite landscape cleared for agriculture.
Mumbulla Mountain from Princes Highway
Google Earth
Similar examples of the landscape that reflect different erosion rates occur across the
region. The view from Piper’s Lookout on the Snowy Mountains Highway at the top of
the steep climb from Bemboka on Brown Mountain shows rolling grassland stretching
almost to the coast 50 km away. As at Cobargo, the grassland represents areas of
fertile soil weathered from Bega Batholith granites, now cleared for pasture.
Forested hills to the left mark the cooked rocks intruded by the granite.
View from Pipers (Brown Mountain) Lookout
The weathered granite is well exposed in road cuttings seen during the ascent to
Piper’s Lookout. The yellow material is a mixture of soft clay and sand formed from
breakdown of minerals in the granite. Occasional large rounded boulders embedded
in this material are all that is left from the once massive rock. When wet, the clay and