Weetootla Gorge, which has a permanent spring, is designated as a ‘special wildlife zone’  due to the diverse array of aquatic life found there. The spring is home to a sub-species of the endangered purple-spotted gudgeon fish, not found anywhere else in the world.

What was interesting on the Weetootla section of the walk was the sense of long time: we walked through hundreds of millions of years of geological history from glaciation times when the earth’s crust was crushed up and jostled for space, when calm seas allowed sediment to settle or be moved around by gentle currents, to be later compressed, squeezed sideways or vertically, or completely worn away.

We walked past 650-800 million year old rocks that form a huge basin under the quartzite and sandstone of the Gammon Ranges, thereby revealing a complex sedimentary record between the Sturtian and Marinoan glacial deposits. The geosites along the walk referred to the Amberoona Formation.

The Marinoan glaciation was a period of worldwide glaciation that lasted from approximately 650 to 632.3 million years ago; an event  that possibly covered the entire planet, hence the name Snowball Earth. This was before the sudden radiation of multicellular bioforms known as the Cambrian explosion.

Since my geological knowledge is nonexistent I could not interpret the geological layers of the Weetoolta Gorge walls that I am walking through; apart from the exposed tillite, a sedimentary rock created from compacted mud, sand and pebbles transported by glaciers.

My geological knowledge is minimal to non-existent. My limited understanding is that the Vulkathunha-Gammon Ranges consist of quartzite and sandstone, and that these ranges are close to the eastern edge of the ancient depression known as the Adelaide Superbasin. Or the Adelaide Geosyncline as it was previously known.