Latitude -36.383615, Longitude 150.071193
Located in the Sapphire Coast Region of NSW, nearest town Bermagui
Source: Montreal Goldfield Tours
For more information regarding tours of the goldfield see www.montrealgoldfield.org.au
The Montreal goldfield is an alluvial deposit. Alluvial means that the gold was moved by water. Older rocks containing the gold were broken down and transported by water into creeks and rivers. The water dropped the particles as it slowed down. The dropped particles are called alluvium. At Montreal this deposit is now about 10-12 metres thick but we don't know how much of it has already been worn away.
Over long periods of geological time the sea falls and rises and the climate become wetter or drier. During a time of low sea level and high rainfall, the river flowed quickly and the heavy gold particles as well as heavy gravels were brought together in the river bed by the action of water and gravity. A thin (20-50cm) coarse gravel zone at the base of the deposit contains almost all the gold. This gold bearing zone was called the "wash" or wash layer by miners. It was the ore the miners "washed" or "puddled" to break up the clay before concentrating the gold.
Later the climate became drier and the river slowed down with less rainfall draining into it. As the water got slower and slower it dropped finer and finer particles. The Montreal deposit shows evidence that this happened. On top of the wash layer the particles get gradually smaller and smaller going towards the top.
There is a lot of clay in the deposit today. Clay comes from the weathering of minerals in the deposit such as feldspar. All of this thick clayey material had to be dug out before the miners could get to the wash layer with the gold!
Gold was first found on the beach at Montreal. It is one of only two places in the southern hemisphere where gold was mined on a beach. The other is in Greymouth in New Zealand. Where did the gold come from? From quartz veins in older rocks located inland. Molten granitic magma formed deep beneath the surface, and intruded the ancient bedrock. In time the magma cooled and hardened to form the local landmarks Mount Dromedary, Little Dromedary, Montague Island and Camel Rock. The cooling process resulted in gold being deposited in quartz veins, which miners call quartz reefs. It is probable that the gold had been worn away from these reefs on Mount Dromedary and washed down the mountain by an ancient river to the Montreal area.
At Montreal, the deposit of alluvium including the gold, rests on older deposited layers of rock. This older rock is referred to as bedrock. The bedrock at Montreal is marine sandstones and shales and these are 450 million years old.
Montreal Goldfield is located near Bermagui on the South Coast of NSW. To visit the site you must go via a guided tour as there are dangerous shafts in the region. Contact Bermagui Visitor Centre (02) 6493 3054 to make enquiries.