Pancake Rocks | |
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![]() Looking south across Pancake Rocks | |
Coordinates: 42°06′50″S171°19′34″E / 42.11389°S 171.32611°E | |
Location | Punakaiki |
Offshore water bodies | Tasman Sea |
Age | Oligocene |
Topo map | Topo50 map BS19 |
The Pancake Rocks and Blowholes are a coastal rock formation at Punakaiki on the West Coast of the South Island of New Zealand. They are a popular visitor attraction.
The Pancake Rocks and Blowholes are located at Dolomite Point, immediately adjacent to the village of Punakaiki, in an area that is protected and forms part of the Paparoa National Park. [1]
The limestone of the Pancake Rocks has been uplifted and then eroded into the current landforms by a combination of two processes – karst erosion (a slow process where chemical erosion of the limestone occurs through the action of water flowing in joints and caverns), and coastal erosion (including the collapse of caverns).
The Pancake Rocks are a heavily eroded limestone formation where the sea bursts through several vertical blowholes during incoming swells, particularly at high tide. The limestone was formed in the Oligocene period (around 22–30 million years old), a period in the geological history of New Zealand where most of the continent of Zealandia was submerged beneath shallow seas. [2] The limestone rocks of the Punakaiki region began forming on the sea floor in warm coastal waters, offshore from a group of low-lying islands. There was a great profusion and diversity of marine organisms growing in these waters, and when these animals died, their shells settled on the sea floor along with small amounts of sand and mud eroded from nearby islands. Over millions of years, vast quantities of shell debris accumulated on the sea floor, eventually forming a thick deposit of nearly pure calcium carbonate. [3]
About 25 million years ago, at the beginning of the Miocene, there was a phase of upward movement of the Earth's crust (known as the Kaikoura Orogeny), that led to the formation of the Southern Alps. Large amounts of sand and mud were eroded from the emerging land and deposited on the sea floor, on top of the shell debris. Over the following 20 million years, as the uplift of the crust continued, the older shell debris became buried under a great thickness of accumulated sand and mud. The high pressures created by the new layers expelled water from the shelly sediment, and this gradually became cemented and lithified to form limestone rock. In the Pliocene, a few million years ago, the Kaikoura Orogeny led to slow folding and faulting of sedimentary layers in the Paparoa region, raising them above sea level. Following this uplift, erosion processes stripped away most of the sedimentary rocks which covered the region. However, at Punakaiki, a downwarping of the crust preserved much of the sedimentary layers. Where the limestone now appears at the surface at Dolomite Point, erosion has removed all the younger mudstones and sandstones. Subsequent erosion of the limestone headland has created the unusual karst landscape. [3]
The regular layering that can be observed in the Pancake Rocks results from a process called stylobedding. Under the influence of high pressure and compaction, small imperfections in the calcium carbonate that forms the limestone tend to aggregate in horizontal planes, in a process known as grain boundary diffusion. This leads to regular bands of stronger rock separated by weaker and more erodable mudstone rock. [2] Thousands of years of rain, wind and spray have mechanically weathered away the surface of the mudstone layers, leaving the limestone layers in relief. [3]
Uplift of the crust is continuing and its recent effects can be seen at Dolomite Point. The flat surface of the headland is in fact an old beach surface, formed at sea level 100,000 years ago and since uplifted by around 35 metres (115 ft). Patches of beach gravel and sand can be found on the headland. [3]
The blowholes at Dolomite Point, Punakaiki have been formed through combined processes of erosion. The action of waves, combined with karst erosion in joints and faults in the limestone rock, leads to the creation of caverns that become sea caves. When the sea cave erodes upwards and towards the land, it can create an opening to the surface. Incoming waves trap air in the sea cave and the air inside the cave becomes compressed, leading to the ejection of air and water upwards from the top of the blowhole. The activity level of the blowhole, depends on factors like tide, sea conditions and the geometry of the caverns. . The best conditions for viewing the blowholes are when there is a high tide, and a large incoming ocean swell. [2]
State Highway 6 is the only through-road on the West Coast, and a large number of visitors pass through Punakaiki. In 2017, it was estimated that there were 450,000 visitors, and many of these take the short walk to view the Pancake Rocks and Blowholes. [4] It has been claimed that the Pancake Rocks are the most photographed rock formations in New Zealand. [5]
The site is accessible by a number of walkways winding through the rock formations. Parts of these are wheelchair-accessible and others are carved into stairways up and down the rock faces. [6]
A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word cave can refer to smaller openings such as sea caves, rock shelters, and grottos, that extend a relatively short distance into the rock and they are called exogene caves. Caves which extend further underground than the opening is wide are called endogene caves.
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus. The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies. Sedimentation may also occur as dissolved minerals precipitate from water solution.
A stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion. Stacks are formed over time by wind and water, processes of coastal geomorphology. They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island. Without the constant presence of water, stacks also form when a natural arch collapses under gravity, due to sub-aerial processes like wind erosion. Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast—the stack. Eventually, erosion will cause the stack to collapse, leaving a stump. Stacks can provide important nesting locations for seabirds, and many are popular for rock climbing.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
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Paparoa National Park is on the west coast of the South Island of New Zealand. The park was established in 1987 and encompasses 430 km2 (170 sq mi). The park ranges from or near the coastline to the peaks of the Paparoa Range. A separate section of the park lies to the north and is centred at Ananui Creek. The park protects a limestone karst area. The park contains several caves, of which Metro Cave / Te Ananui Cave is a commercial tourist attraction. The majority of the park is forested with a wide variety of vegetation. The park was the site of the 1995 Cave Creek disaster where fourteen people died as a result of the collapse of a scenic viewing platform.
Punakaiki is a small village on the West Coast of the South Island of New Zealand. It is located between Westport and Greymouth on State Highway 6, the only through-road on the West Coast. Punakaiki is immediately adjacent to Paparoa National Park, and is also the access point for a popular visitor attraction, the Pancake Rocks and Blowholes.
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In geology, a blowhole or marine geyser is formed as sea caves grow landward and upward into vertical shafts and expose themselves toward the surface, which can result in hydraulic compression of seawater that is released through a port from the top of the blowhole. The geometry of the cave and blowhole along with tide levels and swell conditions determine the height of the spray.
Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). The first geologist to distinguish dolomite from limestone was Déodat Gratet de Dolomieu; a French mineralogist and geologist whom it is named after. He recognized and described the distinct characteristics of dolomite in the late 18th century, differentiating it from limestone.
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A sea cave, also known as a littoral cave, is a type of cave formed primarily by the wave action of the sea. The primary process involved is erosion. Sea caves are found throughout the world, actively forming along present coastlines and as relict sea caves on former coastlines. Some of the largest wave-cut caves in the world are found on the coast of Norway, but are now 100 feet or more above present sea level. These would still be classified as littoral caves. By contrast, in places like Thailand's Phang Nga Bay, solutionally formed caves in limestone have been flooded by the rising sea and are now subject to littoral erosion, representing a new phase of their enlargement.
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