Here’s how science can help you build the perfect sandcastle

Woo! Image: Getty.

Whether we prefer water sports or relaxing with a good book, the humble sandcastle is often a seaside must. But what’s the secret to building a majestic sandcastle that will withstand the tide of time? Luckily, there’s a scientific formula for that.

It all started back in 2004, when a holiday company asked us to investigate the question. As a sedimentologist, someone who studies fragments of rock, I began pondering what kind of beach would work best for castle building. To find out, I compared the sand from the ten most popular beaches in the UK at the time.

Though in truth any sandy beach will do, Torquay came out top with its delightful red sand, closely followed by Bridlington, with Bournemouth, Great Yarmouth and Tenby tied in third. At the bottom of the league was Rhyl.

Having selected a beach one has to find the perfect spot. Now this is a question of taste rather than hard rules. Some might prefer a spot close to the car park with easy access when the rain arrives, while others might want to stay next to a cafe. Others yet might hanker after the secluded fringes of the beach, perhaps sheltered by natural promontories of rock that keep the biting wind at bay.

Torquay harbour. Image: Averoxus/Wikimedia Commons.

Now a castle should be a symbol of military strength, but to stand proud one needs strong sand. The strength of sand depends on the properties of its individual grains and on the water between them. The more angular the grains, the better they will lock together. The more a grain is transported the more rounded it becomes. Microscopic shell fragments work well in this regard. The finer the grains the more they hold the water. And water matters.

Too much water and your sand will flow, too little and it will crumble. You need to get it just right and your castle will stand proud and last. It’s all down to the surface tension of water – the thing that gives the “meniscus”, or skin, to a glass of water and holds down that glass when placed on a wet bar top. The film of water between individual sand grains is what gives sand its strength, too much and it lubricates one grain over the other, but just right and it binds them strong.

The magic formula

Now the experimentation we did suggested that the perfect sandcastle requires one bucket of water to eight buckets of dry sand. Or if you want the magic formula: Water = 0.125 x Sand. So assuming that you don’t have any science gear with you, then you are looking for a spot close to the high tide line – usually marked by a line of seaweed and flotsam – and the low tide line where sand is still visibly wet and the waves are close. But remember that this will change as the tide comes and goes during the day.

High tide line. Image: author provided.

My next tip refers to quality of your tools. In my experience there is a direct correlation between the age of the builder, spade size and the speed at which boredom sets in. Adult helpers find the smallest spade nothing but frustrating, and while young assistants might aspire to use the biggest spade, it is often too big to handle. A selection of tools will keep the workforce in harmony.

The bucket also has to be the perfect size and shape. The best buckets are the simple round ones – not the ones with the fancy turrets which when turned out produce a castle in itself. A round bucket will allow you turn out countless towers and architectural features. A single bucket can be turned out several times to create a large mound from which you carve an amazing tower.

As you build, spare a thought to the story, not just of the castle one is building with its tales of derring-do, but also the story of the sand itself. Each grain is a fragment of rock and contains a story of relict mountains, ancient rivers, dinosaur-infested swamps and seas, of past climates and events which tell the amazing story of our planet. The red sand of Torquay once blew in giant sandstorms, as the area was once part of a desert far greater than that of the Sahara. The sand at Bridlington or Great Yarmouth tells a tale of giant ice sheets and drowned lands below the North Sea.

The ConversationMy next tip refers to size. Yes, size matters – at least in the game of sandcastles. The modest castle with perfect towers, battlements and moat is okay, but it is the huge castles which break the beach horizon that inspire awe and wonderment in people that pass by. Think big! Pebbles, shells, driftwood fragments and feathers all enhance a castle. And let’s face it: a castle is about being seen. And although there may be science behind the humble sandcastle, don’t forget to have fun building it.

Matthew Robert Bennett is professor of environmental and geographical sciences at Bournemouth University.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Was the decline in Liverpool’s historic population really that unusual?

A view of Liverpool from Birkenhead. Image: Getty.

It is often reported that Liverpool’s population halved after the 1930s. But is this true? Or is it a myth?

Often, it’s simply assumed that it’s true. The end. Indeed, proud Londoner Lord Adonis – a leading proponent of the Liverpool-bypassing High Speed 2 railway, current chair of the National Infrastructure Commission, and generally a very influential person – stood on the stairs in Liverpool Town Hall in 2011 and said:

“The population of Liverpool has nearly halved in the last 50 years.”

This raises two questions. Firstly, did the population of the City of Liverpool really nearly halve in the 50 year period to 2011? That’s easy to check using this University of Portsmouth website – so I did just that (even though I knew he was wrong anyway). In 2011, the population of the City of Liverpool was 466,415. Fifty years earlier, in 1961, it was 737,637, which equates to a 37 per cent drop. Oops!

In fact, the City of Liverpool’s peak population was recorded in the 1931 Census as 846,302. Its lowest subsequent figure was recorded in the 2001 Census as 439,428 – which represents a 48 per cent decline from the peak population, over a 70 year period.

Compare this to the population figures for the similarly sized City of Manchester. Its peak population also recorded in the 1931 Census as 748,729, and its lowest subsequent figure was also recorded in the 2001 Census, as 392,830. This also represents a 48 per cent decline from the peak population, over the same 70 year period.

So, as can be seen here, Liverpool is not a special case at all. Which makes me wonder why it is often singled out or portrayed as exceptional in this regard, in the media and, indeed, by some badly briefed politicians. Even London has a similar story to tell, and it is told rather well in this recent article by a Londoner, for the Museum of London. (Editor’s note: It’s one of mine.)

This leads me onto the second question: where have all those people gone: London? The Moon? Mars?

Well, it turns out that the answer is bit boring and obvious actually: after World War 2, lots of people moved to the suburbs. You know: cars, commuter trains, slum clearance, the Blitz, all that stuff. In other words, Liverpool is just like many other places: after the war, this country experienced a depopulation bonanza.


So what form did this movement to the suburbs take, as far as Liverpool was concerned? Well, people moved and were moved to the suburbs of Greater Liverpool, in what are now the outer boroughs of the city region: Halton, Knowsley, St Helens, Sefton, Wirral. Others moved further, to Cheshire West & Chester, West Lancashire, Warrington, even nearby North Wales, as previously discussed here.

In common with many cities, indeed, Liverpool City Council actually built and owned large several ‘New Town’ council estates, to which they moved tens of thousands of people to from Liverpool’s inner districts: Winsford in Cheshire West (where comedian John Bishop grew up), Runcorn in Halton (where comedian John Bishop also grew up), Skelmersdale in West Lancashire, Kirkby in Knowsley. There is nothing unique or sinister here about Liverpool (apart from comedian John Bishop). This was common practice across the country – Indeed, it was central government policy – and resulted in about 160,000 people being ‘removed’ from the Liverpool local authority area.

Many other people also moved to the nearby suburbs of Greater Liverpool to private housing – another trend reflected across the country. It’s worth acknowledging, however, that cities across the world are subject to a level of ‘churn’ in population, whereby many people move out and many people move in, over time, too.

So how did those prominent images of derelict streets in the inner-city part of the City of Liverpool local authority area come about? For that, you have to blame the last Labour government’s over-zealous ‘Housing Market Renewal Initiative’ (HMRI) disaster – and the over enthusiastic participation of the then-Lib Dem controlled city council. On the promise of ‘free’ money from central government, the latter removed hundreds of people from their homes with a view to demolishing the Victorian terraces, and building new replacements. Many of these houses, in truth, were already fully modernised, owner-occupied houses within viable and longstanding communities, as can be seen here in Voelas Street, one of the famous Welsh Streets of Liverpool:

Voelas Street before HMRI implementation. Image: WelshStreets.co.uk.

The same picture after HMRI implementation Image: WelshStreets.co.uk. 

Nonetheless: the council bought the houses and ‘tinned them up’ ready for demolition. Then the coalition Conservative/Lib Dem government, elected in 2010, pulled the plug on the scheme. 

Fast forward to 2017 and many of the condemned houses have been renovated, in a process which is still ongoing. These are over-subscribed when they come to market, suggesting that the idea was never appropriate for Liverpool on that scale. 

At any rate, it turns out that the Liverpool metropolitan population is pretty much the same as it was at its peak in 1931 (depending where the local borough boundaries are arbitrarily drawn). It just begs the question: why are well educated and supposedly clever people misrepresenting the Liverpool metropolis, in particular, in this way so often? Surely they aren’t stupid are they?


And why are some people so determined to always isolate the City of Liverpool from its hinterland, while London is always described in terms of its whole urban area? It just confuses and undermines what would otherwise often be worthwhile comparisons and discussions. Or, to put it another way: “never, ever, compare apples with larger urban zones”.

In a recent Channel 4 documentary, for example, the well-known and respected journalist Michael Burke directly compared the forecast population growths, by 2039, of the City of Liverpool single local authority area against that of the combined 33 local authority areas of Greater London: 42,722 versus 2.187,708. I mean, what bizarre point is such an inappropriate comparison even trying to make? It is like comparing the projected growth of a normal sized-person’s head with the projected growth of the whole of an obese person, over a protracted period.

Having said all that, there is an important sensible conversation to be had as to why the populations of the Greater Liverpool metropolis and others haven’t grown as fast as maybe should have been the case, whilst, in recent times, the Greater London population has been burgeoning. But constantly pitching it as some sort of rare local apocalypse helps no one.

Dave Mail has declared himself CityMetric’s Liverpool City Region correspondent. He will be updating us on the brave new world of Liverpool City Region, mostly monthly, in ‘E-mail from Liverpool City Region’ and he is on twitter @davemail2017.