The story of Gulaga (Mt Dromedary) began in the Ordovician period, nearly 500 million years ago. This was a time when only primitive forms of life existed in the seas and the land itself was bare of any plants or animals. The east coast of NSW lay deep under the sea, its land surfaces up to 500kms inland. Over millions of years, water from the storms lashing the land, totally unprotected by vegetation, carried particles of silt and sand, in great quantities into the sea.
The first layers of sediment became compressed by the newer layers of sediment settling on top and by the weight of the seawater. As the air was squeezed out, the salts in the sea water cemented the grains of sediment together and formed the rock.
Camel Rock is an example of this process. Sculptured from dark chert and slate, it was formed approximately 550 million years ago and is one of the oldest types of rocks in the world. Some of these rocks preserve traces of the primitive marine animals of that time.
Later, perhaps 400 million years ago, at a time when seaweed-like plants were first starting to evolve out of water, an ancient tectonic plate moved westward and raised the seabed, forming a new land surface. Continuing for more than 100 million years, the land was subject to great stresses and pressures, warping, folding and faulting the sediments and altering them into the slates, phyllites, greywacks and similar rocks that exist along the south coast today.
Najenuga and Barunguba
Although this movement of land took place over millions of years, the stress and strain on the earth’s crust caused it to rupture along its weaker seams in intermittent volcanic eruptions.
Gulaga was formed during one of these upheavals about 95 million years ago. At its zenith the volcano rose over 2kms above the surrounding countryside and was fed by a pipe 5km wide, while smaller parasitic cones occurred on the main volcano’s flanks. Remnants of two of these smaller pipes survive today as Little Dromedary (Najenuga) and Montague Island (Barunguba).
Over the 90 million years since the eruptions finished, erosion has removed most of the lavas and ash, leaving behind the harder monzonite and syenite boulders, or tors. The mountain today has an altitude of 797 metres (2500 feet).
The molten rock (magma) being forced up from the centre of the earth into the already folded sedimentary rock helped change the composition of the sedimentary rocks into new ones, called metamorphic rocks or changed rocks. Each insertion of magma had a different chemistry and composition and so a great variety of rock types were produced.
Gold is formed by hot molten quartz solution (like liquid rock) being forced into fissures and cracks in the older rocks. This is reef gold. When the quartz weathers away it breaks up, releasing the gold and other minerals.
The gold is carried down the slopes by streams as alluvial gold. Alluvial gold was discovered in the tertiary sand and gravel found between Wallaga Lake and the sea.
On 21 April 1770, Captain Cook sailed northward along the southern coast of what is now New South Wales in his Majesty’s ship Endeavour. He wrote in his log, “At 6 o’clock we are abreast of a pretty high mountain laying near the shore which on account of its figure I name ‘Mt Dromedary’“.