Whakataki Shore Platform

Whakataki Shore Platform


We’re on the East coast of the North
Island at a place called Castle Point. We’re about 100 kilometers east of
Wellington City. Here we’ve got a spectacular outcrop of these successive turbidity current flow events. And we can see this beautiful tram-line type beds. This very rhythmic cyclicity of alternating sandstones and mudstones. Originally when these rocks were laid down, they were laid down as soft sediments,
and they were horizontal. But through the process of tectonic uplift they’ve been tilted at about a 40 degree angle. Each of the beds we see here, were
originally deposits that came from the landmass. It was shedding a whole series of flows
out into the deep water and these currents flowed along the then sea floor beneath about a thousand metres of water. This would be one flow event to here. Here we’ve got some ripples
and then we’ve got a capping mud for that flow event. And then it goes up into another turbidity
current. So we’re going from oldest deposit, getting
progressively younger as we go up. You can see a whole series of these discrete flow events. As the waves come in they wash through. They erode differentially the harder sandstone from the softer mudstones in between, and in the process of doing that,
it’s breaking off chunks. You can see a lot of these fragments
just sitting on the shore platform here. Then every now and again, the whole
sequence is punctuated by these faults. So we have this linear feature coming
through here and what’s happened is that the rocks have been ruptured along that faultline. The layers have gone like so. There’s a whole series of these faults through the shore platform. They’re an artifact of ancient earth movements. People come from all over to study this area It’s quite a well-known locality to study
deepwater turbidites. It’s a very popular area for geologists to frequent.