A Blast From The Past - The Explosive Origins of the Whitsundays

The story of the Whitsundays begins more than 100 million years ago, when Australia was still part of the ancient supercontinent Gondwana. As the landmass slowly broke apart and drifted, volcanoes became active across what is now Queensland.

The Whitsundays have a fiery past that stretches back tens of millions of years. Around 110 million years ago, this region was part of a geologically active zone. For roughly 37 million years, volcanoes dominated the landscape with explosive eruptions that covered the area in ash and rock. Over time, these layers hardened into solid bedrock, which can still be seen today on islands like Whitsunday and Hook. These greenish-grey to brown rocks have been slowly sculpted by the ocean ever since.

In later periods, less violent volcanic activity pushed molten lava into cracks in the bedrock, creating vertical bands of darker rock called dykes. These are also visible on Hook Island.

Throughout this period, the Earth’s crust kept shifting. As tectonic plates moved and collided, they created mountain ranges across the globe, including parts of what would become the Great Dividing Range. In central Queensland, some of these ancient peaks eventually became the Whitsunday Islands.

These islands are known as continental islands because they were once part of mainland Australia. The Whitsundays are made from the rocky remains of an old mountain range.

Over millions of years, shifting climates caused sea levels to rise and fall with the ice ages. Each time the glaciers advanced or melted, the coastline moved. At one stage, it may have stretched up to 200 kilometres further east than it does today.

About 10,000 years ago, as the last ice age ended, melting glaciers caused sea levels to rise again. The Coral Sea flooded the coastal plains, leaving only the highest peaks and ridges above water, forming the rocky island chain we know today as the Whitsundays.

One of the most iconic features of the region is its vivid blue water. That signature aquamarine hue comes from fine sediment suspended in the sea, which scatters sunlight and creates the vibrant colour that visitors love.

Then there’s the dazzling white sand of Whitehaven Beach. Unlike most local beaches that have coarse sand made from broken coral and shell, Whitehaven’s sand is pure silica. Its origin remains a bit of a mystery, as the surrounding rock doesn’t contain much quartz.

Most scientists believe the sand was carried north along the Queensland coast by ocean currents millions of years ago. It settled at Whitehaven, caught between rocky headlands. Over time, freshwater filtered through the dunes, washing out impurities and leaving behind the fine, brilliant-white sand. When the sea rose again about 10,000 years ago, it reached the base of these ancient dunes, and Whitehaven Beach was born.

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Whitsunday Island landscape. Photo credit: Ruth Puddefoot.

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