NMLA SWIM THE SERPENTINE
SEPTEMBER 2018
On Saturday, a group of current and former NMLA staff, friends and partners swam a mile in the Serpentine as part of the weekend’s open water swimming festival in Hyde Park.
Following a summer of sun-drenched sea and river swims, it was pouring with rain as we made our way through crowds of bemused tourists and displaced geese to the start. It felt distinctly autumnal as we lined up on the edge of the Serpentine in our wetsuits and matching hats to a motivational soundtrack featuring Ricky Martin. After a civilised scrummage at the start, everyone settled into a rhythm for the mile-long lap in the murky greenish-grey water. We circumnavigated Christo’s vast London Mastaba, a stack of 7,506 brightly coloured barrels floating in the centre of the lake, and agreed that our frog’s-eye views of it lent a new appreciation of the piece. As we rounded the final marker buoy and then clambered up the precarious exit ramp, we emerged grinning, enjoying the familiar and addictive endorphin buzz from pushing through the chilly water. A bottle of fizz was opened and shared, and we splashed damply off to the pub to warm up and relive the summer’s swimming exploits.
For anyone considering a discovery of swimming outside (even vicariously!), we would thoroughly recommend Roger Deakin’s wonderful book Waterlog, which tracks a year of swimming in the wild across the UK and has by now inspired thousands of subversive sea, river and lake swims.
A STONE GLOSSARY
MAY 2018
William ‘Strata’ Smith’s 1815 Geological Map, the first nationwide geological map ever published.
We are in the process of choosing the stone to be used for a new building in Cambridge. It has been an apparently exhaustive journey through marbles and limestones from the UK, Europe and beyond. We amass endless samples, and talk in detail to quarrymen, masons and engineers about bed heights, weathering, and reliability of supply, as well as the inevitable costs to quarry the stone, cut it to shape, and fix it together to form a building. One of the most fascinating elements of this process are the specialist terms used to describe building stones and their properties. Below is a list of a few favourite words, ordered to explain the material properties that have so far governed our explorations for this new project.
The Clipsham Quarry at Rutland in Lincolnshire. Clipsham Stone occurs in the Inferior Oolite of the Jurassic System, where it was laid down between 174 and 163 million years ago. Clipsham is a popular building limestone with a characteristic golden colour. We have recently worked with it at Bishop Edward King Chapel in Cuddesdon and the Sultan Nazrin Shah Centre in Oxford.
Bedding plane
Many building stones, including all limestones, are sedimentary rocks, formed by the gradual settlement and compression of underwater sediment over millions of years. The directional way in which they were formed governs their properties and how they can be used as building stones. Most UK limestones must be used ‘naturally bedded’, i.e. orientated in the building in the same way that they were formed in the ground. This means the height of the blocks is limited to the depth of the bed, rarely more than 1m in the UK. ‘Face-bedding’, when blocks are laid so their bedding planes are parallel with the vertical face of the block, can lead to rapid weathering and crumbling.
Metamorphic
A stone that began as another type of rock and changed as a result of exposure to heat and pressure over geological time. Marble was originally limestone, and is chemically identical to it. However, the metamorphic processes changed its physical properties so that it does not have bedding planes, and can be cut and orientated in any direction. This makes it ideal if tall blocks are required.
Precipitation
The chemical process by which Travertine is formed, usually when geothermally heated water is exposed to the air, causing it to degas and carbonate minerals to precipitate out from the water. Although a type of limestone, its distinctive formation means it also doesn’t have bedding planes and is workable in much longer, thinner pieces than sedimentary stones.
Oolitic
A type of limestone made from an amalgamation of individual grains called ooliths. An oolith is a tiny carbonate particle surrounded by concentric layers of calcium carbonate, which were deposited as the ooliths were rolled around on the bed of the clear shallow sea in which the stone was formed. This gives the stone an even structure so it can be cut or sculpted in any direction, a characteristic which makes oolitic stones ‘freestones’. Portland Stone is an oolitic limestone used extensively in London’s historic buildings, perhaps most famously in churches by Cristopher Wren and Nicholas Hawksmoor, including St Paul’s Cathedral and Christ Church Spitalfields.