Glen Helen Gorge, Australia

How did it form?

by Dehne McLaughlin

Published: 7 April 2016 (GMT+10)

The water gap through Glen Helen Gorge.

Why does the Finke River at the Glen Helen Resort flow straight through the range, forming Glen Helen Gorge? Geologists call this a water gap. In Central Australia the Finke River flows across the grain of all the McDonnell Ranges and water gaps are common. In fact, water gaps are a global phenomenon, with more than 1000 across the earth.1 (See Do rivers erode through mountains?)

No one has ever seen a water gap form, so stories that attempt to explain these unexpected geological features are conjecture.

The rims of at least three of the ranges that the Finke River flows through have been ‘dated’ by evolutionary geologists as some 400 million years old. How erosive processes could have continued for so long defies belief. For example, using standard uniformitarian geology, it would only take about 17 million years to erode a whole continent (see Eroding ages: if our continents were old they would no longer be here).

If the Finke River had carved the landscape slowly over long ages, it should have flowed around the barrier instead of through it.

No one has ever seen a water gap form, so stories that attempt to explain these unexpected geological features are conjecture. One popular old-age geological explanation is that the river had already established when the terrain was flat. Then, as the range slowly uplifted, the river slowly cut through the uplifting rock at exactly the right speed, forming the gorge. But, how could such a delicate uplift and erosion relationship be achieved? Uplift of the range should have dammed the river, and we should be able to see accompanying lake deposits and places where the river was diverted. These are rarely found.

Rock cliff face opposite dining area at Glen Helen Lodge (see discussion in article). Click for larger image.

The catastrophic Flood described in the book of Genesis in the Bible easily explains the global phenomenon of water gaps. After the Flood waters reached their peak, and the whole earth was covered with water, the ocean basins began to sink. Over a period of about seven months the Flood waters retreated from the continents, initially eroding the surface flat. These vast flat plateaus can be seen on all continents today. Eventually, the higher parts of the plateaus’ mountain ranges rose above the surface, restricting the flow to channels in between. Cubic kilometres of water, ponded by uplift, would have had to flow in the narrow gaps through the rock barricades formed by the long mountain ranges. These mega water flows provided the erosive power (not available in present day stream flows) to carve water gaps across and into ridges and forming river pathways we see today. Where these gaps were not carved deep enough to allow water to flow, they are known as ‘wind gaps’.

If you drive from the west along Larapinta Drive towards Glen Helen and take a moment to view the shape of the landscape, imagine the water covering the tops of the ranges. It is not hard to visualise the lower lands filled by this water seeking a breakthrough across the ridges to lowering ocean basins to the south. The rock barrier at Glen Helen that the Finke River now flows through after retreating Flood waters cut a water gap, is the massive up-thrusted Heavitree Quartzite. The Todd River also flows through a water gap in the Heavitree Quartzite at Alice Springs. The 300 m (980 ft) deep Ormiston Gorge is also a water gap.2

It is not hard to visualise the lower lands filled by this water seeking a breakthrough across the ridges.

Directly opposite the Glen Helen Resort’s outdoors dining area is a near vertical cliff exposure of the base of the Heavitree Quartzite.3 The quartzite is heavily fractured due to the powerful forces involved in the thrust faulting that formed the cliff (see photo). Note the relatively small volume of debris and boulders (called scree) at the foot of the cliffs. If the cliffs were millions of years old, as evolutionary geologists tell us, there should be an extensive boulder-filled scree slope at the base of the cliffs. This lack of scree indicates these cliffs are young, confirming the recent carving of these water gaps by receding Flood waters.

Once we understand how Noah’s Flood makes sense of the landscape, it changes the way we see our world. And for many people, that gives a new appreciation for the trustworthiness of the Bible and stimulates them to revisit its message.