Topic: Cliffs - Rapanui

Topic type:

RAPANUI    Rock cliffs.

Rapanui is south of Te Kawau Pa.  It is separated from Te Kawau Pa for some distance with the beaches inbetween being inaccessible.

NOTE:  I have divided Rapanui into two parts.

The northern part is RAPANUI NORTH.  Its cliffs are similar to those at Te Kawau Pa in that they have a high degree of folding.  They are composed of interbedded mudstones and sandstones with the top layer being derived from sand and volcanic ash.  The cliffs are low to medium in height and the beach is short with an impassable bluff at the northern boundary.  The beach is mostly sandy.  A small sand dune area lies immediately north of the Rapanui Stream which forms the southern boundary.

The southern part is RAPANUI SOUTH.  This is a much longer beach.  It extends from immediately south of the Rapanui Stream (the northern boundary), to just north of the cave at Pilot Point.  The cliffs are generally higher than Rapanui North.  Importantly, they do not exhibit elaborate folding.  Aside from this feature, they are composed of the same embedded mudstones and sandstones, topped off with a layer of sand and volcanic ash.

Though subject to cliff falls, due to the relative ‘straight line’ nature of the beach, erosion activity is not high compared to some other area along the Tongaporutu coastline.  Preferential cliff base carving though is quite active as it is along most of this coastline.

There are two rock stacks, Petrel Rock and the R-shaped rock.  (There is a petrel colony above and immediately south of Petrel Rock).  The R-shaped rock is just north of the only small, semi-enclosed all-tide beach (Driftwood Cove), where driftwood can accumulate.  There are a number of passageways and arches of varying sizes.  The beach, though normally well endowed with sand, can, like the rest of the Tongaporutu coastline, be badly stripped of sand.  Specifically, all of Tongaporutu’s beaches have a near surface bedrock base which can be wholly or partly exposed during storms.  That is, the beaches can be stripped almost wholly clean of sand or completely covered with sand, with varying stages inbetween.

2002

12 May 2002   PHO2008-866

Rapanui South.  This was taken before the project began.  It was taken from the cliff top on the O’Sullivans’ farm and looks north along the beach.  The R shaped rock stack is in the distance.

2003

13.7.2003   PHO2008-942, 946

Rapanui South.  While photographing at Pilot Point, I took a couple of photos looking north along the coast.  These images show the cliffs at Rapanui South beach from its southern end.

8.10.2003   PHO2008-273

Rapanui South.  This view looks south along the beach.  White Cliffs is in the distance.

23.10.2003   PHO2008-279, 294-295, 298, 301, 1068-1069, 1071, 1075

Rapanui South.  I took various images showing some of the different facets of the cliffs, including some of the arches and the R-shaped rock stack.

26.10.2003   PHO2008-323-324

Rapanui North.  These two images looking towards Rapanui North beach were taken on the same afternoon that I did cliff sequencing photography on Rapanui South beach.

26.10.2003   PHO2008-325-333, 336-347, 349, 351, 1090

CLIFF SEQUENCING, Rapanui South.  This was straight-forward documenting of the cliffs.  Nothing of note re collapses was observed.  The R-shaped rock stack and the Petrel rock stack are also shown for reference purposes.

4.11.2003   PHO2008-354-360, 367-369, 371-373

CLIFF SEQUENCING, Rapanui North.  Straight-forward documenting of the cliffs.  These cliffs though were not as high as those found at Rapanui South.  The Rapanui North cliffs have more in common with those at Te Kawau Pa, being highly folded.

 

2004

21.3.2004   PHO2008-760-761

Rapanui South.   There was a minor rock fall immediately south of Driftwood Cove.  (PHO2008-760).  Further down I observed a partial cliff collapse.  (PHO2008-761).

28.3.2004   PHO2008-775, 1244

Rapanui South.  PHO2008-775 looks south over a deeply indented cove.  Pilot Point is partially obscured beyond this.  PHO2008-1244 looks north over the cliffs.

2007

25.11.2007   PHO2011-1105, 1109, 1112, 1114-1116

Rapanui South.  I hadn’t visited this beach for some time, so today was it.

2008

31.8.2008   PHO2011-1302, 1307, 1311, 1317

Rapanui South.  After photographing the aftermath of the Super-Storm event of last month, I checked out the cliffs part way along the beach at Rapanui South.  I didn’t observe anything of note.

12.11.2008   PHO2011-1369-1387

CLIFF SEQUENCING, Rapanui South.  These cliffs are relatively stable as far as I have observed.  While photographing the cliffs, I noticed that there is an active area at the Petrel Colony fence.  There is a through arch here and a large fault-line running close to the lower part of the fence.  A blind arch is forming here.  When I say ‘relatively stable’, this is relative compared to some other areas such as the Three Sisters Beach which is currently in a state of ongoing collapse (July 2008 to the current date, June 2009).

This cliff sequencing is not as thorough as the one done in October 2003 due to me being unable to get as far out as last time.  That is, due to weather and the beach topography, the low tide wave-line was closer to shore.  There were also some mid-beach salt-water ‘lakes’ in places.

15.12.2008   PHO2011-1471-1472

Rapanui North.  I wanted to do cliff sequencing, but with the weather being yuksville, I walked down to the northern impassable bluff, ventured out onto the flattened rock platform at its base, and took a long shot of Rapanui North beach, looking south.  I also took a long shot looking north.  I didn’t notice any fresh cliff falls.

2010

11.8.2010   PHO2011-1825, 1827, 1829

Rapanui South.  I didn’t notice any cliff collapses, but I did see two distinct boulder fields at the base of the cliffs located roughly half way along the beach travelling north from Pilot Point.  They were separate cliff collapse debris fields.  From what I could tell, the collapses weren’t recent.  For the most part, the cliffs at Rapanui South are relatively stable.  This to mean that though collapses and minor rock falls do occur, the cliffs are not highly active when compared to the Three Sisters Beach.

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