New study dates Australia's K'gari Island
Two hundred kilometers North of Brisbane, Australia, is K’gari Island, the largest sand island in the world. A new study from researchers at USU suggests the formation of K’gari was a crucial step in the birth of the Great Barrier Reef.
Tammy Rittenour, a professor in USU’s Department of Geosciences and a coauthor of the study, said her team used a technique called Optically Stimulated Luminescence Dating to estimate the age of K’gari’s sand dunes.
“The bottom of the first sand dune deposits were around a million years old, which is really old for loose sand,” Rittenour said.
This date places the formation of K’gari during the Middle Pleistocene Transition, a time when the size and pace of global ice storage in glaciers changed. Rittenour said this provides a likely explanation for how K’gari developed: The increased size of rapidly melting and freezing glaciers caused changing sea levels that then shifted sand landward forming K’gari’s numerous sand dunes.
In turn, Rittenour said the birth of K’gari likely provided the conditions for the construction of the Great Barrier Reef. She said corals are extremely sensitive to sand and K’gari buffers the Great Barrier Reef from sandy water.
“Which when you have these long shore currents in the ocean, they hit that island and it routes the sand off the continental slope protecting the area to the North where the Great Barrier Reef is,” Rittenour said.
In a world with changing sea levels, Rittenour says this discovery about the past has important implications for protecting the Great Barrier Reef today.