Clifton Cliffs to Cape Kidnappers

The geological history of the Cape Kidnappers cliffs goes back 5 million years to a time when the area was at the bottom of the sea. These oldest rocks are located below Cape Kidnappers itself and consist of blue-grey mudstone that was laid down in deep water.
The rocks from the shelter towards Black Reef are younger – about 3 – 4 million years old, and consist of shallower water (30 – 50 m depth) soft sandstones with oysters and scallops. Occasionally fossil whale bones and shark’s teeth have been found in these rocks.
From Black Reef towards Clifton, the yellow coloured layer at the base of the cliff is about 3 million years old and was laid down in even shallower water, about 10 – 20m deep. The shore was getting close at this time and shells are quite common in this layer.
A gap in the sequence of rocks (an unconformity) occurs between about 3 to 1 million years ago. It is thought that either ocean currents prevented sediments from being preserved during this time, or that the area had been raised above sea level. This unconformity (time gap) can be seen at the top of the yellow coloured layer.
Next come shallow marine and coastal rocks interbedded with very distinct pale volcanic pumice layers. These came from huge eruptions in the Taupo Volcanic Zone. In places there are tree stumps from coastal swamps. There are some spectacular faults offsetting some of the layers seen in the cliffs. The youngest rocks of all (closest to Clifton) are river gravels with interesting cross bedding structures and lenses of finer sediment.
The Cape is a sacred (tapu) site, as in Maori legend it represents the fish hook of Maui that he used to pull the North Island, (Te-Ika-a-Maui), out of the sea.

If you walk, or take a tractor ride along the shore from Clifton, you will be going back in time in reverse of the description given above.
• The gravel beds are initially about 300,000 years old and record large ancient rivers that flowed across the landscape. They drained rapidly growing mountain ranges to the west.
• You might also find layers of peat and buried tree stumps from when forests grew here.
• The sandy mudstone layers are from when the area was covered by the ocean. Have a look for fossil shells, in these beds. They lived in estuarine or very shallow-marine environments.
• The repeated changes from gravel to peat to mudstone layers took place over 100,000 year cycles, recording the advance and then melting of massive Northern Hemisphere ice sheets, which changed global sea levels.
• Look also for white-coloured layers. These are volcanic ash deposits called ignimbrites (“glowing clouds”) that have travelled all the way from volcanoes in the Mangakino area of the Taupo Volcanic Zone. Some of these deposits flowed at near-supersonic speeds across the land surface to get here! Can you see colour changes in the rocks below the ignimbrites? They show that some of these volcanic deposits were still hot enough to cook the layers of sediment beneath them.
• The flat land surface along the top of the cliffs is a marine terrace that was at sea level about 100 000 years ago, and has been uplifted due to tectonic activity.
• You can see that there is continually active erosion of these cliffs, with evidence of very large rockfalls.