Lost in the Outback

The Olympic Games in Sydney are turning the world’s eyes on a continent that seems strange and mysterious to many people. Even to native Australians, the land holds stunning surprises. Only recently did they learn about the existence of one of the most amazing landscapes in the world: the Bungle Bungle Range.

The Bungle Bungles is a place where thousands of colorful rock formations shaped like beehives and striped like tigers rise in tiers. The result is a mountain range that looks like no other.

Somehow, this place managed to remain a literal blank spot on the Australian map until the 1980s. Before that, only a group of local Aborigines and a small number of other Australians knew about it.

REMOTE SECRET

To see the Bungle Bungles for myself, I joined a safari outfit on a journey to Purnululu National Park, deep in the Aussie Outback. It began in Kununurra, a town about 250 kilometers (155 miles) by road north of the Bungles.

My trip to the Bungles showed me why they had escaped widespread notice for so long. The Bungles are surrounded by many square kilometers of rugged country, which discouraged exploration. Even people who got close could have easily missed the beehives because the rolling landscape hides them from view. “You could be 10 miles away and not really know what was in there,” said Robert Young, a senior research fellow in the School of Geosciences at the University of Wollongong.

On my visit, we camped beside Picaninny Creek, a stream that emerges from the southern end of the massif(mountain mass). After setting up my tent, I gazed out at the vista I had come many bumpy miles in a four-wheel-drive vehicle to see: a seemingly endless expanse of beehive-shaped formations carved out of sandstone. Most astounding to me were the horizontal layers of orange and black that looked for all the world like tiger stripes.

DISSOLVED CEMENT

According to Young, the rock of the Bungle Bungles began forming 400 million years ago. Streams and rivers laid down layers of sand in a growing pile that eventually might have reached several thousand feet thick. The enormous pressure from all that material slowly turned the sand into sandstone. And there it lay for many millions of years, buried by even newer rock layers deposited on top.

Later, erosion gradually stripped away the overlying rock, exposing the sandstone about 20 million years ago. Streams then began cutting into the rock–the start of the process that would create the “beehives.”

Why did the sandstone erode into such unusual shapes? To find out, Young used an electron microscope to peer between the tiny quartz grains in the sandstone. Quartz is a tough, crystalline mineral made of silicon dioxide (Si[O.sub.2]). In sandstone, the quartz grains that form most of the rock are held together by a kind of cement. In the case of the Bungle Bungles sandstone, that cement consists of a compound called silica. Like quartz itself, the silica cement is also made from Si[O.sub.2].

Examining the Bungles’ quartz grains, Young determined that rainwater seeping into the rock had slowly dissolved most of the silica cement between the quartz grains. At that point, only the tightly interlocking shapes of the quartz grains themselves held the rock together.

The lack of cement makes the rock very friable; it crumbles easily under foot. But the interlocking grains make the rock strong in compression, which means that it can maintain tall vertical cliffs without falling down. The result is rock that can be carved easily by streams but that stands up in tall towers and beehives and in long, thin ridges.

BANDS OF ALGAE

There’s more to the mystique of the Bungle Bungle Range than the shape of its rock formations. Equally alluring is the orange-and-black tiger striping.

The colors, it turns out, are only skin deep; the actual sandstone is a cream color. The coating is silica cement that has leached out of the rock to form a hard veneer. Small amounts of clay and iron in the silica veneer give the beehives their orange color.

The dark tiger stripes come from algae, simple plants that live in the water or in moist places on land. The algae snuggle into tiny holes and crevices within the coarsest bands of the Bungle Bungles sandstone.

As I gazed at the striped formations during a hike into Picaninny Gorge, I wasn’t thinking of geological details. I was simply overwhelmed by the grandeur of this Outback wilderness. And as I walked up the canyon, my amazement only increased. The beehive formations gave way to cliffs, and the canyon snaked in broad S-curves as it penetrated deeper into the Bungle Bungle Range. The environment seemed to capture the essence of Australia: isolated, empty, breathtakingly luminous, and wondrously strange.

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