Contemporary Jurassic

This is the new south Piccadilly Green Park Station pavilion, completed in 2011 for the 2012 London Olympic Games. I visited it this weekend to see the fossil filled Portland Stone used for its walls and copings. Green Park lies on Piccadilly at the intersection of the Jubilee, Piccadilly and Victoria Lines and was a key node for Olympic visitors transferring from the Jubilee line to get to Stratford. It was opened in 1906 and rebuilt in 1933 and was previously best known as the site of an IRA bombing in 1975.

The recent renovations include the new entrance pavilion inserted between the Royal Park and Piccadilly. This is made up of four small buildings supporting a single copper-lined inverted catenary roof unifying them into a single composition. The pavilion frames views between park and street, creates small pools of space for resting and looking, provides a slightly elevated plinth where one can rent a Boris bike or just hang out, and channels movement in a series of spatial layers parallel to the street to an enlarged staircase dropping underground.

The building was designed by Capita Architecture, the architectural brand of Capita Symonds and sculptor John Maine RA was commissioned by Art on the Underground to create a new artwork on the station structure. His work, Sea Strata, conceptualised the building as a geological outcrop, focused on the geology of the Portland stone cladding and the granite of the pavilion’s paving.

Portland stone is a limestone found on the island of Portland that has been used for many of London’s buildings since the early 1600s, particularly after the Great Fire of 1666. The degree of cementation in the stone allows it to resist the effects of the weather, but makes it difficult to work. This is why it is favoured as a monumental architectural stone and has been used for a number of London’s iconic buildings – St Pauls, the East Side of Buckingham Palace etc. It is ubiquitous in Piccadilly, where Green Park Station is located.

Portland Stone was formed in the seabed towards the end of the Jurassic period, around 145 million years ago, when Portland was much closer to the equator than it is today. A chemical reaction in the warm, shallow seas caused calcium and bicarbonate ions to combine, forming a muddy calcareous precipitate. Minute particles of sand or small organisms lying close to the sea floor gradually became coated with this fine-grained calcium carbonate. Overtime more and more calcium carbonate accumulated around these nuclei in concentric layers, forming small spheres (less than a mm in diameter). Countless billions of these spherical sediments, known as “ooids” or “ooliths’” became buried and partially cemented together by more calcium carbonate, resulting in the oolith limestone we now call Portland Stone. For more information on the geology of Portland Stone click here.

Two samples of Jurassic Portland Stone used at Green Park Station

All of the Green Park Station pavilion’s stone comes from Albion Stone, a privately owned company that has quarried the stone on Portland for three quarters of a century. It is the largest limestone masonry works in the UK and leases much of the land it quarries from The Crown Estate. Stone was first quarried by hand with sledgehammers, twibels, kivels and axes. Once deeper beds were exposed, stones were extracted by drilling small holes into the rock and blasting blocks loose with gunpowder. Since 1999, Albion has been using stone cutting equipment developed for Tuscany’s marble quarries, eliminating the need for blasting. Quarry faces are dry-cut using diamond tipped chain saw like blades and stones displaced using hydrobags – steel bags that are inflated with water to dislodge the stone. To cut these large unevenly dislodged blocks of stone, they are either sawn, or metals plugs are inserted, exerting a tensile stress into the stone, which eventually induced a linear fracture. Since 2002, Albion has been extracting an increasing percentage of its stone my mining, using the same modern stone cutting equipment it uses in its quarries. Bowers, one of its sites has been operational since the late 1700’s. In 2002, it became the site of the first Portland Stone mine and today extraction is completely underground.

Albion Stone’s Bowers Quarry. Source: http://www.albionstone.com/portland-stone/quarry-and-mine/

Its other quarry, Jordan’s, has been worked since the late 1800s; a large portion of its reserves lie under the grounds of the local cricket club and will also be mined.

Albion Stone’s Jordans Mine. Source: http://www.albionstone.com/portland-stone/quarry-and-mine/

Albion claims that mining has far less impact on the environment and has a far smaller carbon footprint that quarrying. The Green Park Station pavilion uses four types of Albion stone: Jordan’s Basebed, Jordan’s Whitbed, Fancy Beach Whitbed, Grove Whitbed and Jordan’s Roach, all of which are described in more detail on Albion’s website. For further details click here.

After stone is extracted, it is subject to a number of factory processes. It is first sawed into slabs. Secondary sawing than cuts the slabs into stones for cladding, pavers or cubes for further processing. Stone used for masonry is shaped utilizing profiling saws, planers or skilled mason’s handwork. Profiling saws typically produce long runs of stones like string courses or copings and would have been used for the Green Park Station pavilion’s coping. Planers, adapted from engineering workshops produce highly accurate stone mouldings using zinc templates and masons use a wide variety of tools to produce intricate stone carvings. All stones go through a final finishing process that uses grit to remove all saw cutting and tool marks.

Maine’s work at Green Park draws attention to the unique character of Portland Stone, as found in its geological state and exhibits the geological and fabrication processes that have gone into the making of the building. He works with limestone blocks that are 145 million years old, full of pockmarks and fossils. The station’s anonymous service buildings, which have very few doors or other features, take on the appearance of natural stone outcrops from the Jurassic era, collapsing time, technique and aesthetic intent.

Stone cladding is set in bands or layers that continue across all the buildings to suggest the strata of the stone as it occurs in its geological state. At eye level, a frieze of drawn shapes derived from enlarged Portland fossils has been incised using contemporary fabrication techniques.

Below this, a band of Roach stone incorporates a drip course moulding that coincides with the carved coping of the low walls throughout and further emphasises the composition into geological strata.

Maine describes his project in the following way on Art on the Underground’s website:

I wanted to the use the Portland stone of the walls to explore the natural composition of the rock and to draw out the internal structure of the material, revealing the fossil remains of marine creatures from 150 million years ago. I imagined the four small buildings as outcrops with strata linking across from one to another. By rounding the corners of the buildings, they take on a more solid feel, and the various bands wrapping around the walls emphasize the natural layers, which you would find in a Portland quarry.

I selected a bed of stone that is particularly rich in fossils; the so-called ‘spiral gastropods’, which look like small arrows made from sharp cone forms. In the stone they may be no more than 8 cms long, but I examined them closely and decided to draw them on a much larger scale. I have incised these fossil enlargement drawings on a band of clear stone that runs around all the buildings.

The skirting of the buildings is made of much harder granite, from the famous old quarries at Kemnay in Aberdeenshire. The floor is paved with granite from various countries, each slab marked with an incised spiral. In the eighteenth century there was a rectangular reservoir at this very spot, where people promenaded. The turbulent paving now acts as a reminder of that surface of water, and also refers to the layering of fossils that once formed the sea bed.

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2 responses to “Contemporary Jurassic

  1. Pingback: The History of Portland Stone - Portland Stone Steps·

  2. Pingback: The History of Portland Stone - Portland Stone History·

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