Australia's beaches show off the unique journey and makeup of sand

Aussies love the beach and with our nation ringed by coastline, it's easy to see why. 

But have you ever looked closely at the sand and wondered how it got there?

Every grain tells a story of time and transformation.

While it may look pale from afar, up close it's a colourful mix of minerals and fragments.

University of WA school of earth sciences professor Annette George says, in geology terms, sand refers to "particles between 0.06 and 2 millimetres".

To unlock its secrets, you need to magnify it.

From bush to beach

Professor George says much of our beach sand starts as inland rock, broken down and carried by rivers to the coast.

"Once that sediment reaches the coast, the material gets distributed by waves and currents."

In Geraldton, 420 kilometre north of Perth, the beach near Chapman River has pink, sparkly grains that have come from rocks further inland carried by the river — linking bush to beach in a dynamic cycle.

Under the microscope, these grains resemble tiny, intricate rocks.

Nature's sand factory

Marine engineer Wade Greenaway says about 60 per cent of Geraldton's fine sand is biogenic (produced by living organisms) and is formed from marine life in seagrass meadows.

"Little creatures break down in seagrass beds. Seagrasses are really important. They're a sediment source," Mr Greenaway says.

"Limestone is a bit more of an ancient material but that does break down as well."

Unique beaches

No two beaches are the same.

"For nine months of the year the sand moves from south to north and that's typical of the WA coastline," Mr Greenaway says.

"As the infrastructure on the coast has built up, it causes that interference with that long shore drift."

He says to restore balance, Midwest Ports transfers sand each year between beaches.

"When the port and wharf expanded, it blocked that natural flow, causing sand to build up," Mr Greenaway says.

"It's like a conveyor belt — we now have to manually feed it to restore natural sediment pathways."

Midwest Ports also monitors sand composition annually.

"We're measuring the size and makeup of the sand to understand beach conditions like wind or wave energy," Mr Greenaway says.

"It supports our sand bypassing program and helps maintain consistency across the coastline."

History and human impact

Geraldton's coastal dynamics have long shaped its development.

Mr Greenaway's late grandfather, Gordon Greenaway, recalled sediment issues as far back as the early 20th century, when the railway jetty first altered natural sand movement.

Chosen as a port in the 1850s for its natural harbour, Geraldton has evolved, with deeper berths and regular dredging to suit larger ships.

Wade Greenaway says people often overlooked the complex, shifting nature of beaches.

"You always hear people say the beach isn't where it used to be, but it's always changing. We only see a small snapshot in our lifetimes," he says.

Sand's never-ending journey

The story of sand doesn't stop at the shoreline.

Professor George says, over time, sand grains may become sandstone, rise again through geological uplift, and erode, starting the cycle anew.

"Once buried [1.5 to 2km below the Earth's surface] the sand basically becomes a rock and it keeps being buried," she says.

"Then eventually if it's lucky enough it will come back up to Earth's surface and then that process begins again."

As Mr Greenaway puts it, managing sand sustainably is vital: not just for ports, but for preserving the natural beauty we all love.