Sand is composed of silica – the most common mineral on Earth.
ON a recent day flight back to Kuching from KLIA, I marvelled at the kilometres of pristine beaches on the east coast of Peninsular Malaysia and as the plane descended over Borneo Island.
Not a thought of tourist developments passed through my mind, which concentrated, there and then, on ever rising sea-levels. How did those beaches get where they are?
Exactly 50 years ago, I sat my final papers in the Examination Schools at Oxford University. I distinctly remember one question on the geomorphology paper – “The sea is a consumer and not a producer of sand.” Discuss. This quote was taken from a Breton geomorphologist, Ferroniere, whose book I had fortunately read in French.
It is often a common fallacy to believe that where headland and cliffs are eroded by the sea that all the sandy material will be deposited on nearby beaches.
Actually only a minute fraction will end up there for the sea is a transporting agent.
Origins of beach sand
Most sandy and pebbly beaches in Europe and in most parts of the world, including Sabah and Sarawak, are the result of tides gradually pushing material from the seabed onshore, with currents then sorting out the material.
During the relatively recent Pleistocene (Ice Ages), from 1.4 million to 11,000 years ago, the sea level inevitably fell as water was contained in land ice-masses and continental ice sheets.
However, the glacial periods were interspersed with Inter Glacial phases when the ice melted and the meltwaters flowed down to the much lower sea beds and plains.
For instance, the English Channel separating Great Britain from Europe was just a barren plain above sea level with a huge meltwater river, the Proto Rhine, flowing south as far as almost today’s Bay of Biscay. Millions of tonnes of sand gravel and rocks were deposited on this plain (today’s seabed).
As climate change saw the deterioration of the Eurasian and American continental ice sheets, so the sea level gradually rose.
In doing so, these seabed sediments from the previous relatively dry sea floor were bulldozed towards the shore to create our present day beaches. Much the same has happened in Borneo, when the South China Sea succumbed to ice on the land and then rose as the ice sheets melted.
Today, tidal currents and wave action move sand grains and pebbles through the process of longshore drift. The direction of this movement is determined by the prevalent winds at various times of the year.
This can easily be observed on Damai, Santubong, and Sematan beaches, all dependent on the wave directions, force, and wind strengths hitting the beach.
What after all is sand?
It is composed of the most common mineral on Earth – silica, and is nigh indestructible. It can take many forms such as sandstone rock, once deposited in river deltas and then uplifted into mountains, hills and cliffs
In some forms, such as agate and rose quartz, it is made into semi-precious jewellery.
On my most recent visit to Kuala Lumpur, I stayed with friends in their high rise apartment. From their balcony, I marvelled at the plethora of tower blocks surrounding them and moreover the millions of tons of sand that been added to cement to create the mortar for their construction.
The logistics of getting this mortar to such extraordinary sky-high altitudes defeated me.
Our houses are reinforced and bonded by sand. Equally sand is an essential ingredient of glass window panes, mirrors, kitchen items, and spectacles, to name but a few commodities.
I well remember once visiting the famous Pilkington glassworks in St Helens, Lancashire, UK, and was amazed that this glass was manufactured from a deposit of local glacial outwash sands, dumped there 11,000 years previously.
A huge amount of sand is used in concrete and glass for high rise buildings such as these in Kuala Lumpur. — Photo by Mark Tan
Building sand
I have witnessed extraction of red sand from local land sand deposits in Devon, UK and at sandstone quarries where it is then crushed, such as in Batu Pahat, Johor.
I fetch the red sand from my local quarry to point the slate slabs of my house and have seen boat loads of sand departing from Johor for Singapore for land reclamation and building construction purposes there.
I well remember, during my first visit to Singapore 24 years ago, a local geographer teacher friend said, en route from Changi Airport to the city centre along the East Coast Highway, “As a child, where there is now land that was my beach, Alan!” She pointed west and east to tower blocks and a distant seawall.
Singapore was not unlike the China expansions on some of the disputed Spratly Group of islands, where sand offshore has been dredged to infill land behind sea fortifications. Such dredging can lead to short term consequences.
In 1909, with the planned expansion of Devonport Dockyard in the southwest of England to accommodate naval refit vessels, huge quantities of sand and shingle were dredged from the post glacial deposits offshore from south Devon.
Already two cliff villages, Beesands and Hallsands, were dangerously near the eroding cliff edge. By 1920, one village had disappeared and the other is perilously close to total destruction. Why did this happen? Dredging deepened the waters offshore so that the incoming wave energy was not dissipated through friction, for a huge chunk of the shingle and sand off the seabed had been removed.
Global research
A report, by Dutch engineers and coastal geomorphologists, on the state of global beaches in this April’s edition of ‘Scientific Reports’ revealed that efforts to protect coastal areas and reclaim land from the sea has created an extra 3,600 square km of beaches in the last 30 years, mainly in Dubai, China, and Singapore.
Against this 700,000km of sandy coastlines have been washed away. Over 25 per cent of the world’s beaches are being eroded at a rate of more than 0.5 metres a year. This figure applies to 6,000km of beaches.
The submergence of Maldivian beaches, at a phenomenal rate, readily springs to mind as the sea level rises.
No burying our heads
Climate change is with us and sea levels are rising thus explaining the loss of sand and pebbles from our beaches, as storms are more frequent and stronger, combing material down a beach on the backwash of waves.
In many holiday resorts and hotels, artificial beaches have been created by dredging offshore sand. Whilst there are a few such beaches in Sabah and Sarawak, the very long sandy beach at the famous seaside resort of Blackpool, in northwest England, is annually replenished by lorry loads of sand transported from Morecambe Bay to the north of the town.
Such beaches are not immune from natural processes and are only temporary creations. Through time, offshore dredging and piping of the removed sand onshore will inevitably heighten the plane of wave attack.
The forces of nature are indeed awesome and every grain of sand counts to not only the beach profile and visitors’ comforts but moreover to the flora and fauna of the natural world, living in sandy and undersea environments depending on a sandy beach for their very existence.
A seaside holiday or a day trip to our local beaches is always a family treat, for a swim in the sea or even to build a sandcastle.
Do make good use of these sandy shorelines whilst they are still there for, in three or four decades’ time, such beauty spots along our coasts may no longer exist. Whatever, please only leave behind your footprints in the sand.