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Deep Time and Out of Time


Michael Tubby

With the clearing of the rain, the scientists have all been very eager to get back our into the field and exploring new sites within the national park, however I’ve stayed at base camp today to finish off my projects. Today is our last full day at the camp, and it’s sad to think that this experience will soon be over. We talk and collaborate and discuss our big plans for new projects, but it’s optimism seasoned with sorrow.

During my time in Rungulla, I have really enjoyed exploring the geology and interpreting the stories of the rocks. My university education was equal parts zoology and geology (I’ve always loved dinosaurs) and I’ve always paid attention to the rocks around me. While exploring the park I’ve consulted my geological map app and was amazed to learn that the base layer of rocks here are very old meta basalts and mudstones that are all over 1.6 billion years old! That’s older than the first fossils of complex organisms by over a billion years! It makes a person feel very humble in the grand scheme of things. These old rocks show layering and folding on grand scale, but are often unappreciated as they are buried deep under a much younger layer.

Above these very old rocks are a much younger group of layers from the Jurassic period – the time of dinosaurs. These are mostly sandstones formed in river systems very similar to the current Gilbert River – sandy with flooding that brings bigger chunks of rocks from upstream. I can tell because the layers in the sandstone pinch off and cut across each other – evidence of underwater sand dunes that only form in fast flowing water.

But what about the rocks in between the 1.6 billion year old basalts and muds and the 180 million year old sandstones? That is a 1.4 billion year gap! If geological history were a book, then almost all of the middle pages have been pulled out. What interesting stories would those missing rock layers tell?