Topic: Caves - Three Sisters Cave System
THE THREE SISTERS CAVE SYSTEM (Two caves) - The Three Sisters Beach
The Three Sisters beach starts on the southern side of the Tongaporutu River and travelling south, ends at the Point.
There are several smallish blind caves plus a number of through passageway caves. Passageway or corridor caves are different to through arches which tend to be shorter (but not always) in length. In some instances they could perhaps be classified as one and the same, (arch/corridor caves). Borderline instances occur where large cliff promontories are bisected by a through passageway which could just as equally be called an arch. It depends on how pedantic you want to be.
With regards to the through-going cave that houses the Maori carvings, I classified them under cliffs. This is because the cave itself was unremarkable and was perhaps a causal factor in the massive full cliff section collapse that I observed on 12.11.08.
I have documented one cave in particular because it shares a common feature with that of the Te Kawau Pa cave. That is, it has a huge, high, overhanging open bowl/dome at its north-western entrance. As at 2003, it was a blind cave. However, on the south-western cliff wall to the right of this cave, a small, blind passageway cave was being carved out by preferential wave action. The roof height of this was around 30 feet. The entrance was small compared to that of the large, open, blind cave.
The rock strata at the Three Sisters cave, particularly those higher up, were well fractured. Leading immediately around to the north of the entrance, there was a through-going arch/corridor cave cum. Its roof was around 15 feet in height. This then turned around into a small blind indentation in the base of the cliff - a mini-blind cave.
These features are all part of the Three Sisters Cave System, but when I refer to the Cave, I am referring to the main, large blind cave with the high open bowl.
The Three Sisters cave is situated immediately south of the Three Sisters rock stacks and a little north of Elephant Rock.
The image here shows part of the northern entrance of the Three Sisters’ blind cave. More importantly at this juncture however, is its location on the Three Sisters Beach. (This was also the first time that I saw the Maori carvings in the small through cave to the rear of the Three Sisters).
Soft light enabled me to take a good interior photo of the Three Sisters cave. There were quite a few medium sized rocks on the cave floor, possibly from a fairly recent partial cliff fall. With regards to the through corridor cave immediately north of the main cave, well, its shape reminded me of the closed bridges I saw in the film, ‘Bridges of Madison County’ with Meryl Streep and Clint Eastwood. Green algae on the cliff walls shone in the diffused light.
6.10.2003 PHO2008-249, 253
I have taken a location shot showing Elephant rock in the background. The internal view of the main cave shows the right-hand cave wall (seaward side of cave), just inside the entrance. Lots of rocks on the cave floor. The beaches were heavily scoured out after the alpha storm of 29.9.03. Some of the material may be due to this, and some could be due to a rock fall.
The two geologists in the foreground give some idea as to scale with regards to the northern entrance of the Three Sisters Cave.
Partial roof collapse material was observed in the main cave.
18.7.2004 PHO2008-1307, 1310
Evolution of roof collapse material, plus an external view of the cave’s northern entrance.
24.7.2005 PHO2008-1381, 1387
The south-western forming blind corridor cave has now breached the seaward side wall of the high, open-domed blind cave, close to its entrance. Debris material is visible. Due to this, the Three Sisters Cave is NOW A THROUGH-GOING CAVE. I am not sure exactly when the main cave wall was breached, but it would have been quite recent due to the presence of debris. PHO2008-1387 shows an internal view of the newly formed adjoining, through-going corridor cave.
20.8.2005 PHO2008-1388-1390, 1396, 1400, 1404,1407
This photograph of the new corridor cave entrance was taken from just inside the large cave that it had smashed through into. (PHO2008-1407).
As it was great light, I also look a number of photos of some of the smaller, blind caves on the beach.
21.8.2005 PHO2007-216, PHO2008-1421-1423
Thanks to soft light, I was able to photograph the whole of the Three Sisters cave showing the new passageway cave entrance. I then documented the passageway cave from inside it. However, due to the narrow corridor cave’s curvature, its south-western entrance was not visible. PHO2008-1422 was taken from the corridor cave’s south-western entrance. It looks towards the main cave (obscured due to angle of view). PHO2008-1423 features the ‘Madison Bridges’ corridor cave immediately to the north of the cave’s northern entrance.
I also photographed the Maori Cave Carvings. They are in a small through cave to the rear of the Three Sisters. (PHO2007-216).
ALPHA STORM. The walls of the cave were smothered with sea foam. It was as if the cave had been frothing at the mouth. Sea foam was also flying around in a wind-whipped frenzy.
A small chunk of cliff to the right of the cave’s internal entrance looked like it had recently been punched out. Light not good for photography.
Internal view of the main cave. In particular the clean part of the cliff that looked like it had shaved off recently. No debris was present. I then recorded the continuing evolution of the corridor cave’s exit point into the main cave.
The whole cave is continuing to evolve, especially the right hand side corridor cave exit. This is eroding out more. High sand level.
A full cliff face collapse. From what I could tell, The large cave roof had partially collapsed. It also took with it A good chunk of the seaward facing cliff that houses the smaller passageway cave. When I see things like this, I am both excited at the new find, but also sad because it is a loss. I estimated that this collapse had occurred within the past 12 hours due to the extreme freshness of the debris field. A large amount of soil was present. Much of the soil was below the high tide mark and was staining the surrounding pools. Soil was also still present on rocks that will be washed off when the tide comes back in. A live flax bush sat plonked atop the collapsed cliff pile and I could see a coprosma tree further back inside the cave. The sand on the beach was all scoured out.
12.11.2008 PHO1399, 1404
A full cliff section collapse occurred to the rear of the Three Sisters, completely destroying the Maori carvings cave. (PHO2011-1399). At the Three Sisters cave, apart from a few rocks, all of the cliff collapse material that I had observed on 15.10.08 had vanished. If you had not seen the original collapse, you would never have known that one had occurred. Superficially, the cave itself appeared unchanged. The photo taken is an external one, not close up.
23.11.2008 PHO2011-1412-1413, 1419
At the cave I heard bits of cliff material dropping off from above. However, I had checked before coming this close in that any falling material would occur on the outside, which it did. Lots of rocks on the cave floor. Some of this material will be leftovers from the 15.10.08 cave collapse, but most will be debris that has migrated over from the nearby cliff section collapse I observed on 12.11.08. I also took a photo from the landward side of the northern through corridor cave. This view looks back towards the Three Sisters cave proper.
14.12.2008 PHO2011-1427, 1434
CLIFF SEQUENCING. I took a distance photo from the cave’s northern side to show its location on the beach. PHO2011-1434 shows an oblique view of the passageway’s cave south-western entrance. A person is standing conveniently close by for scale.
22.7.2009 PHO2011-1620, 1623-1625
At the main north-western entrance, the seaward cliff wall that leads to the through corridor cave entry into the large, open cave appears to be in the process of being carved out (thinned). I also took some images from the south-western entrance.
I had primarily come up to Tonga to record rough weather wave action on the dune at the gap. Before venturing down onto the beach however, I took some images from the clifftop. This view, from above the cliff section collapse site, shows the outer wall of the Maori carvings cave to the immediate right of the New Sister. It also shows a partial view of the Three Sisters cave’s northern entrance.
At the Three Sisters cave, it appeared remarkably ‘clean’. That is, due to the very high sand cover, there were no rocks visible on the cave floor. Also, the through going corridor cave had full sand cover. This area usually has pools of water.
The outer wall remnant of the defunct Maori Carvings cave is still intact, although it is gradually succumbing to the sea. This cave was destroyed in the massive cliff section collapse that I observed on 12.11.08.
There has been a partial cliff collapse immediately south of the large cliff collapse opposite Elephant Rock. I mention it here because there is a particularly large open blind cave at this site. There was a common garden blind open cave prior to the cliff collapse, but it now appears to be much enlarged. It will be interesting to follow its evolution. I couldn’t get close to photograph internally as rock falls large enough to kill were in progress.
(Digital camera). There had been a fairly substantial partial cliff collapse at the Three Sisters Cave. This was on the landward side of the large, open bowl entrance located on the northern side of the cave. As I was with some members of the Taranaki Geological Society, I was able to get some people in some of the images for scale. I estimated it had occurred during the past couple of weeks.
I didn’t actually visit the Three Sisters Beach today. However, from Pilot Point, it appeared as if the large overhanging dome to the Three Sisters Cave had collapsed. It also looked like the New Sister had gone. However, until I can actually visit and confirm or otherwise either of the above, this is just speculation. I do know that there has been a very recent cliff collapse or rock stack or cave collapse on the Three Sisters Beach because of the live flax bushes that have washed up at Pilot Point.
At the Three Sisters Cave there hadn’t been a recent roof collapse as I had thought on the 27th. However, the debris field from the collapse observed on the 28th March remained, but apart from a large boulder, it had diminished. The New Sister remained intact.