Limestone - the porous rock
About 25 million years ago this area was part of a wide shallow sea (around 100 metres in depth). Over time the fossil remains of dead sea life accumulated on the seafloor. These thick layers of accumulated sediment formed the Otekaike Limestone that dominates the landscape around Duntroon.
Limestone is a porous rock. Where these pores are connected together, groundwater, and in some instances,
water from the surface can move through the limestone. Where this water is slightly acidic, it can dissolve
calcium carbonate in the limestone, sometimes leading to cave formation. Where the ground surface (roof of
the cave) collapses into the dissolved open space below, a sinkhole results.
Where does the water come from?
The waters of the Maerewhenua River originate in the Kākaunui/Kakanui Mountains (to the southwest). The river then follows the orientation of the Maerewhenua Fault to the Waitaki River. Yet, not all the water is above ground. Some surface water filters down into the limestone southwest of Duntroon. The water then travels underground – remerging in the Duntroon wetlands. Brewery Hole is the result of the collapse of a cave that had formed by dissolution of the limestone by this groundwater.
Importance of water
The water that runs through the Brewery Hole has been important to the Duntroon village. In the past the local blacksmith used this water. By submerging the metal into water, known as ‘quenching’, the blacksmith controls the strength of the metal. In the early 1970s the water was used as the water source for the Duntroon Water Scheme.
This has since changed, and the water for the town is now drawn from the Waitaki River. A local community group look after the Brewery Hole today. It is thanks to that group that the public can view this site.
The Maerewhenua River a few kilometres southwest from here.
Yardley’s Blacksmith in the 1920s.
© Collection of the Waitaki Archive. Id 109049
Karst topography describes land that has dissolution features such as sinkholes.
Water can move through limestone underground and emerge at the surface as springs.
The name originated from around 1869-1872 when a local brewery was established to service gold miners in this area.
Nicol’s Blacksmith Shop website has further interesting information on this interesting feature.
Please be aware the following hazards include: Fall (into) hazard, unstable rock.
Park your vehicle in between the Vanished World Centre and Nicol's Blacksmith Shop in Duntroon.
Protection and guardianship are at the heart of the Geopark philosophy. We ask you to treat this site with respect, do not remove anything from this site and preserve it for our future generations.