The Organ Pipes are the outstanding example of columnar jointed basalt in the Dunedin area accessible to the public.
When molten volcanic rock cools, the rock contracts and causes regular hairline cracks.
At the Organ Pipes this cooling process has resulted in the formation of four-to-six-sided columns of rock, some of which are over 2m long.
These in time became exposed and weathered.
Early photos show an organ-like formation with large numbers of separate columns.
Unfortunately earthquakes and vandalism have caused many of the larger columns to fall over.
However, the remaining outcrop and pile of broken columns, some of which have been used to line the track, are still impressive .
Various informal tracks have been made to the Organ Pipes, but a benched track was constructed in the early 1980s as part of the Skyline Walkway.
The car park is part of an old quarry, so at the start of the track there is a wooden staircase that leads up the quarry wall.
A steep climb zig-zags up through scrubby bush to emerge into an open area.
The track then sidles round the flank of the hill where there is a view to the north.
Continue through dense native bush and stop to explore an overhanging rock which would make a rather uncomfortable bivvy.
From the track there are views of the scree of broken Organ Pipes above.
The track then hairpins back up to the base of a scree of fallen rock from the Organ Pipes.
A viewing platform was built here in 1984 but was damaged and removed in 1996.
The platform had been severely damaged by a rockfall presumably caused by a recent earthquake.
It is possible to clamber over the rocks to get a view to the north and west.
Above the scree are the few standing columns of rock.
Be careful when walking on the scree as the rocks are liable to move.
Return back down the track to the car park.
Mt Cargill option (2 hours, 4.1 km, 270m) Continue from the Organ Pipes to Mt Cargill .
The track crosses a boggy saddle between Mt Holmes and Buttars Peak.
A side trip to Buttars Peak is well worthwhile.
There are hairline cracks in the summit rocks similar to the Organ Pipes but no standing columns.
Return back down the track to the car park.
• This is an extract from Dunedin Tracks and Trails, an illustrated guide to Dunedin walks, tramps and mountain bike routes by Antony Hamel.
It is available at Dunedin bookshops and the Visitor Centre.
Walk 2: The Organ Pipes
Drive north on George St, in Dunedin, to the Gardens and turn left into North Rd (2.5km).
Follow North Rd and turn right up the hill at the Normanby Tavern (5km).
The winding road climbs up the right hand side of Mt Cargill until a sharp left hand turn at the Upper Junction intersection (8.4km).
Taking the left hand fork, continue around the side of the mountain to the Peninsula Lookout (10.5km).
Take time to admire the view before continuing to the Organ Pipes car park (11.2km).
