|Location:||Paparoa National Park. Bullock Creek, follow river uphill from its estuary north of Punakaiki. About 6km (1.5h) walk from the road.|
|Classification:||Losing Stream Oligocene to Miocene limestones|
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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Bullock Creek is a typical river for this area. It emerges in the Southern Alps, fed by the enormous rainfalls of the west coast (2.3m at Punakaiki, but up to 3m inland). Flowing down to the sea, the river has to cross a small area of limestone, enclosed by insoluble rocks like granite. As soon as the water reaches the limestone, it stats to dissolve the rock and form caves and other karst features. And after the caves underground have become big enough the water flows continually underground. Only during the first time, the now dry riverbed is reactivated by floods, which are too big for the cave underground.
This is the situation at Bullock Creek. A walk on the river trail will show you many karst features, but the sinks are probably the most difficult to see and the most mysterious. First the water will emerge from the gravel of the river bed, which is dry further upwards. This is the resurgence. And after some time walking along the dry river there will be water agian. This are the last remains of the vanishing stream. Still further up the river is as big as below. However, not all the water sinking at Bullock Creek will flow through this valley to the sea. A part takes a detour through Cave Creek.
The trail along the river is the old Inland Pack Track, which was used when the road was not yet built. There are two starting points, at Pororari River Bridge or at Bullock Creek road. Beneath the submergence and resurgence of Bullock Creek, Cave Creek is located close to the trail. It is signposted. If you want to do the whole section of the Inland Pack Track you should plan about five hours.