Hamersley Gorge Walk, Karijini NP (Top trail)

Walking Through Deep Time

Karijini National Park is internationally recognised for its geological significance. Its rocks preserve evidence of ancient oceans, the emergence of oxygen-rich environments and some of the earliest chapters of Earth's history.

The park's banded iron formations, dramatic gorge systems and exceptional exposures of ancient rock provide scientists with invaluable insights into geological processes that occurred billions of years ago. For visitors, Karijini offers a rare opportunity to walk through landscapes that reveal the deep history of our planet in extraordinary detail.

A Turning Point in the Story of Life on Earth

The rocks exposed throughout Karijini formed between approximately 2.5 and 2.0 billion years ago during the Precambrian Era. At that time, the region lay beneath ancient oceans where layers of iron-rich sediments and silica accumulated on the seafloor.

These sediments eventually formed the banded iron formations that dominate the Hamersley Range. Alternating layers of iron minerals and silica created distinctive red, silver and black bands that remain visible in many of Karijini's gorge walls today. 

As visually spectacular as they are, these banded iron formations also tell the story of one of the most important events in Earth's history—the rise of oxygen in the atmosphere.

More than two billion years ago, microscopic photosynthetic organisms began releasing oxygen into the oceans. This oxygen reacted with dissolved iron in seawater, causing iron minerals to precipitate and settle onto the seafloor. Repeated cycles of deposition produced the characteristic bands visible within the rocks today, providing evidence of the Great Oxidation Event - a period when oxygen levels increased dramatically and permanently changed Earth's atmosphere, paving the way for the evolution of complex life.

Karijini National Park therefore preserves not only an important geological record but also a record of a transformative chapter in the history of life on Earth.

Formation of the Gorges

While the rocks themselves are billions of years old, Karijini's famous gorges are geologically much younger.

Over millions of years, uplift of the Hamersley Plateau increased river gradients and enabled streams to cut deeply into the resistant iron-rich rocks. Seasonal rainfall and flowing water gradually carved the narrow, steep-sided gorges that characterise the park today.

Gorges such as Dales Gorge, Hancock Gorge, Weano Gorge, Knox Gorge and Joffre Gorge reveal spectacular cross-sections through ancient rock layers. In some places, gorge walls rise more than 100 metres above the valley floor, exposing rock formations that would otherwise remain hidden beneath the surface.

The narrow slot canyons found in several gorges formed where water exploited fractures and weaknesses within the rock, progressively deepening and widening these natural pathways.

Waterfalls, Pools and Travertine Terraces

Karijini's waterfalls and permanent pools add another layer to the park's geological story.

Water flowing through fractures in the rock dissolves minerals before emerging as springs or flowing into gorge systems. Over time, minerals carried in the water can precipitate to form deposits known as travertine, creating terraces and natural dams around some pools and waterfalls.

Features such as Fortescue Falls and Fern Pool demonstrate the interaction between geology, groundwater and surface water. These permanent water sources support unique ecosystems that contrast sharply with the surrounding arid landscape.