A Clive special from 2015, re-published because it is worth re-reading.
Ever since I saw my first pictures of Ball’s Pyramid, I wanted to know more about this isolated and amazing structure.
The pyramid is named after Lieutenant Henry Lidgbird Ball, who discovered it in 1788. On the same voyage, Ball also discovered Lord Howe Island.
In the book The Voyage Of Governor Phillip To Botany Bay With An Account Of The Establishment Of The Colonies Of Port Jackson And Norfolk Island (1789), Arthur Phillip gives this description of Ball’s pyramid:
“The island is in the form of a crescent, the convex side towards the north-east. Two points at first supposed to be separate islands, proved to be high mountains on its south-west end, the southernmost of which was named Mount Gower, and the other Mount Lidgbird; between these mountains there is a very deep valley, which obtained the name of Erskine Valley; the south-east point was called Point King, and the north-west point, Point Phillip. The land between these two points forms the concave side of the island facing the south-west, and is lined with a sandy beach, which is guarded against the sea by a reef of coral rock, at the distance of half a mile from the beach, through which there are several small openings for boats; but it is to be regretted that the depth of water within the reef no where exceeds four feet. They found no fresh water on the island…” 
Ball’s Pyramid is the world’s tallest volcanic stack. It is part of the Lord Howe Island Marine Park, which is recorded by UNESCO as a World Heritage Site of global natural significance.
Ball’s Pyramid is an erosional remnant of a shield volcano and caldera that according to potassium-argon dating formed about 7 million years ago. It is located approximately 20 kilometres (12 mi) southeast of Lord Howe Island in the Pacific Ocean. It is 562 metres (1,844 ft) high, while measuring only 1,100 metres (3,600 ft) in length and 300 metres (980 ft) across, making it the tallest volcanic stack in the world.
The Pyramid is located in the Tasman Sea in the south west Pacific Ocean approximately 700 km (420 nm) north east of Sydney, New South Wales. The Lord Howe Island group comprises Lord Howe Island, the Admiralty Islands, Mutton Bird Island, Ball’s Pyramid, and some coral reefs. The Lord Howe Island Group is the top of Lord Howe Rise (an underwater plateau) and sits on the western edge of a large shield volcano which erupted about seven million years ago. The ancient volcano rises more than 2000 metres above the seabed on the western flank of the Lord Howe Rise, a major physiographic feature of the south west Pacific area. The sea has reclaimed most of the original volcano, leaving the Lord Howe Island group. The landscape is spectacular with the volcanic mountains of Mt Gower (875 m) and Mt Lidgbird (777 m) in the south and the northern hills rising virtually sheer from the sea.
Ball’s Pyramid also has a few satellite islands. Observatory Rock and Wheatsheaf Islet lie close by. Like Lord Howe Island and the Lord Howe seamount chain, Ball’s Pyramid is based on the Lord Howe Rise, part of the submerged continent of Zealandia.
Ball’s Pyramid is composed of nearly horizontally-bedded basalt lava flows, the remnants of a volcanic plug formed in a former vent of a volcano. After the eruption of the shield volcano, the slopes became truncated to form a broad submarine shelf.
Geologists believe that there were two main volcanic episodes in the formation of the Lord Howe Island group. Most of the volcanic activity took place some 6.9 million years ago, and comprised several volcanic vents, ultimately producing a large shield volcano about 30 km in diameter. It is thought that the volcano’s maximum height above sea level was about 1,000 metres.
Around 6.3 million years ago the area around the main vent collapsed and left a huge oval-shaped pit or caldera, perhaps five kilometres long, two kilometres wide, and 900 metres deep. At this time further volcanic material pushed up from beneath the earth’s crust to infill the caldera in a series of horizontal lava flows, varying from one to thirty metres in thickness. In this second period of volcanic activity, the basalt rocks were harder and more erosion resistant, standing today as the southern mountains which still rise to 875 metres above sea level. (9)
Ball’s Pyramid is located in the centre of the shelf, which forms a platform that is about 20 km from north to south, and averages 10 km wide. The average water depth above the shelf is around 50 metres. A similar but slightly larger shelf surrounds Lord Howe Island, and the two platforms are separated by a canyon that exceeds 500 m in depth. Eventually due to erosion by waves the volcanoes will be completely gone, unless a coral reef forms around it and protects its shoreline.
Ball’s Pyramid is home to a small population of Lord Howe Island stick insects, a species previously thought to be extinct. The Lord Howe Island batfish is also only found at this location. (8)
There is speculation that Balls Pyramid rock is aligned in the same direction as a mega-tsunami that hit Bass Point and possibly the South Island of New Zealand. A tsunami tens of metres high could cause the strange features observed on Balls Pyramid. (2)
Ball’s Pyramid cliffs are devoid of talus and the feature has an aerodynamic shape aligned to other smaller, sculptured forms on the main island.
Further odd features are widespread within the Australian coastal environment. Lord Howe Island provides evidence that tsunamis did not originate locally along the South Coast of New South Wales, but were ubiquitous in the Tasman Sea. For example, Lord Howe Island is dominated by numerous sculptured bedrock features at varying scales and orientations – the latter without apparent structural control. Streamlined inverted keel-like features are prominent on the eastern side of the island indicating a tsunami wave approach from the Kermadec trench north of New Zealand. (3)
The Lord Howe shield volcano was built thus. Tholeiitic lavas of the North Ridge Basalt comprise the main shield building phase and were erupted about 6.9 Ma ago. The Boat Harbour Breccia probably formed within the throat of the volcano and, together with the North Ridge Basalt, is intruded by numerous basaltic dykes, which grade into a cone sheet complex near the main vent. Large scale collapse of the summit area of the volcano produced a caldera which was filled rapidly by lavas of the Mount Lidgbird Basalt some 6.4 Ma ago, bringing to a close the volcanic history of Lord Howe Island. The shield volcano thus was built during a short interval in the late Miocene.
Palaeomagnetic data show that the North Ridge Basalt and the Mount Lidgbird Basalt were erupted during periods when the geomagnetic field had normal polarity, and that their formation was separated by at least one interval of reversed polarity when the dykes and cone sheets were emplaced. The directions of magnetisation for the lavas and intrusives are such that, palaeomagnetically, no movement of Lord Howe Island is detected since its formation. (6)
The shelf which surrounds the Lord Howe Island Group extends slightly beyond 3 nautical miles where there is then a very steep ‘drop-off’ representing a major discontinuity between the shallow inshore and shelf environments and the deep sea. The main structure of the seamount is contained within 12 nm of the shoreline of Lord Howe Island. Recent seabed multi-beam swath mapping surveys conducted around Lord Howe Island and Ball’s Pyramid indicate a high degree of benthic complexity. Data from surveys show a rugged terrain on the submarine flanks of these volcanic islands, including down-slope flow structures (probably old lava flows), canyons and numerous volcanic cones and pinnacles, many 200-300 metres high.
Lord Howe Island is the subaerial part of a large seamount which lies at the southern end of a northerly‐trending line of volcanic seamounts extending for more than 1000 km. The Lord Howe seamount chain probably was produced by movement of the Australian lithospheric plate over a magma source or hot spot located below the plate within the upper mantle. Other data suggest that the Australian plate is moving N at about 6 cm/a and from this it is predicted that the seamount underlying Nova Bank, at the northern end of the chain, was constructed by volcanic activity about 23 Ma ago. Similarly, if volcanism were to occur now in the Lord Howe seamount chain its location would probably be around 400 km S of Lord Howe Island (6)
Lord Howe Island and adjacent Balls Pyramid are composed of the basalts that erupted around 6-7 million years ago and sit near the middle of broad shelves on separate peaks of one major volcanic edifice. The central part of the Lord Howe Island is covered by calcarenite that was deposited primarily as dunes (eolianite). Towering plunging cliffs characterise the resistant Mount Lidgbird Basalt, in some cases fringed with large talus slopes. On less resistant rock structures, or where nearshore topography means greater wave force as a result of waves breaking, there are shore platforms. Slumping cliffs abut broad erosional platforms on the poorly lithified calcarenite. (7)
In summary I would like to say much of this article is culled and rewritten from various papers listed below in the References. I’m not a scientist and rely on the writing of others. I hope one day to visit this amazing place but, sadly, it is unlikely. It has fascinated me for years and I wanted to share with you my interest in the place, hence my little article for you all.
Hope you enjoyed learning about it!
References and further reading
http://en.wikipedia.org/wiki/Ball%27s_Pyramid [accessed 26/5/14]
During 2001 Dr Edward Bryant from the University of Wollongong published a book “Tsunami: The Underrated Hazard”. He proposes that the best explanation for a range of odd geological features along the south east coast of Australia is that at least one large tsunami struck the coastline around 1500 AD. The book describes these geological features and the mechanisms by which they can be produced by tsunami. The book also covers historical accounts around the world, the physicsc of tsunami, causes of tsunami and a review of the risk to coastal populations.
Geological Indicators of Large Tsunami in Australia A. BRYANT and J. NOTT
A management strategy for Lord Howe Island for the Australian voluntary conservation movement. A Paradise in Peril. John Sinclair, May, 2002
Lord Howe Island Marine Park Proposal, March 2000
McDougalla, B. J. J. Embletonab & D. B. Stoneac (1981) Origin and evolution of Lord Howe Island, Southwest Pacific Ocean . Journal of the Geological Society of Australia, Volume 28, Issue 1-2, pages 155-176.
Colin D. Woodroffe, David M. Kennedy, Brendan P. Brooke, and Mark E. Dickson (2006) Geomorphological Evolution of Lord Howe Island and Carbonate Production at the Latitudinal Limit to Reef Growth. Journal of Coastal Research: Volume 22, Issue 1: pp. 188 – 201.
LORD HOWE RISE AREA, OFFSHORE AUSTRALIA: PRELIMINARY RESULTS OF A CO-OPERATIVE FEDERAL REPUBLIC OF GERMANY/AUSTRALIA GEOPHYSICAL SURVEY. J.B. Willcox, P.A. Symonds, D. Bennett , &K. Hinz
Published for the Bureau of Mineral Resources, Geology and Geophysics by the Australian Government Publishing Service, Commonwealth of Australia, 1981
(Finally) Completed by Clive Ruffle 3 June 2015!