Topic: Cliffs - Twin Creeks

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The cliffs at Twin Creeks, as with the rest of the cliffs along the Tongaporutu coastline, are composed of Interbedded mudstone and sandstone cliffs with the usual top layer of sand and volcanic ash (‘soil’).  The main difference between specific locations being one of soil ratio ratio and folding.

Twin Creeks is just south of Beach Two.  A large, impassable bluff separates the two.  An even more extensive and equally impassable bluff, separates the southern end of Twin Creeks from Whitecliffs.  It is a highly active erosion site.

The cliffs at Twin Creeks are bisected by a small, open bay that is easily accessible from the east-facing portion of the mainland.  At this juncture, the land is low lying and slumping.  Twin Creeks also has two streams that empty out into it, hence its name.  One creek is on the northern boundary, while the other is located at the southern boundary.  A rock stack sits in the middle of the bay.  The northern cliffs slope/slump sharply downwards towards the beach and culminate in a large arch.  The southern cliffs are fairly evenly high and have a large, open bowl cave at the northern boundary of the southern cliffs.  (The cave is blind at this stage).  The southern cliffs curve around into another bay.  This has a large, impassable bluff – the southern boundary proper of Twin Creeks.  White Cliffs is beyond this point.

The Maori name for this impassable bluff is Ruataniwha.  This relates to sea-dwelling monsters.  However, it also became known as Rigby’s Point after Constable John Rigby drowned while attempting to swim three horses around it in 1883.

 

2001


3 January 2001  

PHO2008-825

 

This shows the wall-like structure of some of the cliffs.  This cliff section is at the northern end of Twin Creeks.  The view looks south with White Cliffs in the background.

 

2003

19 November 2003  

PHO2008-410

 

This view from the Top Paddock gives an overview looking north along the Twin Creeks Beach.

 

9 December 2003  

PHO2008-469-471

PHO2008-1154

Though the conditions were uncomfortable to work in, they gave the photos a different look.  PHO2008-471 shows the arch with the northern creek passing through it.

 

2004

4 January 2004  

PHO2008-1184

 

I particularly wanted to photograph Twin Creeks at sunset.  Though not really successful as a dawn shoot would show it in better light, the image does show the Middle Rock and the arch.

 

 

8 February 2004  

PHO2008-655-670

PHO2008-1206-1208

 

CLIFF SEQUENCING.  Due to choppy sea conditions, directed by an onshore westerly, I couldn’t get as much separation distance as I wanted from the cliffs.  This meant that I had to photograph at an angle, rather than straight on. When the cliffs yielded to the bay however, the farmland was much further back so I could do straight, (directly opposite) sequencing there.  On the southern side, a milky brown stream oozed across part of the beach from a collapsed bank that was slowly melting under the onslaught of water.

 

29 February 2004  

PHO2008-685-686

PHO2008-688-691

 

 

SUPER-STORM EVENT.  Super-Storm Three.  The sea state was wild, huge, frothy and belligerent.  There was nothing pussycat about it.  The road was fractured in part.  Only a matter of time now before it joined the slumping land it traversed and slid down onto the beach below.  Also, on the landward side of the northern arch there was a full cliff/landslide collapse.  The northern stream drains onto the beach close by and travels down to and through the arch.  Mud and a huge log pile were evident at the stream/beach boundary.  Logs are usually resident here, but the locals were joined by newcomers.

 

2005

 

6 November 2005  

PHO2008-1476

1478-1480

1482-1485

1488-1489

 

On the landward side of the northern arch leading around to the northern stream, a lot of erosion was evident.  Also, some large boulders along with a cliff slide appeared to be fairly recent in origin.  Perhaps induced by the alpha storm of 19.9.05.

 

2006

4 January 2006  

PHO2007-217

PHO2008-1539-1542

 

I wanted to record rough conditions at Twin Creeks.

 

2007

27 October 2007  

PHO2011-1071

PHO2011-1074, PHO2011-1075

PHO2011-1077, PHO2011-1078, PHO2011-1079

PHO2011-1081

PHO2011-1083

PHO2011-1086

 

I noticed more of the landward cliff just beyond the northern arch had sent a lot of debris down.  This particular spot is in a state of semi-permanent collapse as it slumps down towards the beach.  (Landward side, not seaward side).  More of the roadside bank had eroded away.  On the beach proper and just north of the northern arch, a lower section of the cliff is being eaten into, creating a blind overhang/cave.  This will eventually form a new arch to replace the current one when it is ultimately destroyed as the parent cliff continues its downward slide onto the beach.

 

At the huge, open bowl southern entrance of the blind corridor cave, an arch is being carved out of the lower cliff.

 

 

 

2008

 

 

9.3.2008   PHO2011-1182-1183

 

At the southern creek, the seaward side hillside is slumping into it.  This, like its northern counter-part is in a highly active erosion state.  The land side is also eroding away.  On the hillside up from the northern arch, another smallish slip now accompanies the massive land slips that have occurred there.  At the base of the large, old slip are the remains of a huge tree trunk.  This is possibly part of an ancient forest that existed here in the past.

6.4.2008   PHO2011-1196, 1198.

 

I made a quick visit to Twin Creeks specifically to document the evolution of the Middle Rock.  (See Section Six on Rock Stacks).  The arch is also losing mass.

 

 

3.6.2008   PHO2011-1237-1238

 

The arch that was forming at the southern open bowl entrance to the southern cave has now been destroyed.  This probably occurred quite recently because debris is still visible.  I first observed this arch on 27.10.07. 

 

 

12.10.2008   PHO2011-1337-1338, 1343-1346, 1349

 

There was a huge slip to the north of the northern arch.  I had earlier observed a fault-line and had assumed that this would fail in the not too distant future.  Sure enough, the slip had come away precisely along this line.  The vegetation, consisting mainly of reeds and flaxes were still alive.  Another fault-line tracking north along the seaward (land) side of the northern creek, is the site of future land slumping down into the creek.  Part of the bank at the site where the northern creek and the beach proper meet, is being preferentially carved out by waves and stream outflow.  Erosion is particularly bad during flood conditions.

 

More erosion had occurred at the road, and this is in severe danger of collapsing down onto the beach.  The Gibbs have already foreseen this and have constructed another metalled road behind the high landward hill.

 

On the beach, checking on the arch, it appeared to be thinning due to chunks of it being bashed off by waves.  More ominously, I noticed a crack at the top of the arch in the middle.  Once this collapses, a new rock stack will be created like Pat’s Stack at Pilot Point, or, it will be completely destroyed like the Pilot Point Arch.  (Both of these features were created and destroyed during the super-storm event of July 2008).

 

Further north along this short beach, I noticed  a largish chunk had recently fallen from the highest knob on the cliff.  No debris whatsoever remained.  It is interested to note that I have never observed a cliff collapse on the seaward side of Twin Creeks to date.  Nor have I ever observed any debris material, save for the collapsed cave entrance arch on 3.6.08.  The Middle Rock rock stack is being destroyed.

 

Due to the highly volatile wave action and backwash here, any cliff fall material would very quickly be destroyed.  Most of the observable erosion taking place here is occurring on the landward side, whereas at all the other sites, the erosion is on the seaward side.  The two creeks at Twin Creeks are the major carving agents at work here.

 

 

15.12.2008   PHO2011-1477

 

The road at Twin Creeks has now been eaten into and the seaward section is cracked and splitting apart.  (The photo shows Twin Creeks in storm conditions.  It doesn’t show the road).

 

 

 

2009

 

 

20.4.2009   PHO2011-1760, 1762

 

A panoramic photo shows the main Twin Creeks beach.  Beyond the northern bluff is another bay.  This is shown in a photo taken from the Top Paddock.  This bay, plus the short beach on the opposite side of the northern arch are all part of Twin Creeks.  The northern arch appeared to be thinner and the large land slip just north of it appeared relatively stable for the time being.

 

 

18.10.2009   PHO2011-1913-1915, 1918-1919

 

THE LARGE NORTHERN ARCH HAS BEEN DESTROYED.  No debris was present.  The outer stump of the arch is all that remains.  As I last visited here in April 09, I can’t date when it was destroyed.  It could have been during the past couple of months as the weather has been quite volatile lately.  Also, a large land slip had occurred immediately north of where the arch had been.  This continued downwards towards where the northern creek enters the beach.  It is eroding preferentially northwards.  This whole area is slumping and unstable.

 

I also took a couple of images from the paddock overlooking the southern part of Twin Creeks to Twin Creeks proper and north up the coast.  One was with the zoom (digital camera) at wide angle while the second image was with the telephoto end of the zoom.

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