Larapintine Sea EarthCache

Dreams of an inland sea attracted the early explorers to central Australia. But all they found were glimmering mirages and the giant ripples of sand dunes.

However, this area was once covered by the Larapintine Sea, a tropical sea teeming with life.

John McDouall Stuart ascended and named Mount Stuart on 23 April 1860. He was attempting to locate the centre of Australia and calculated Mount Stuart as that centre point, halfway between the north and south coast and almost halfway between the west and east coast. It was later renamed Central Mount Stuart.

Stuart was also searching for a rumoured inland sea that attracted so many early explorers into Australia's red centre. But neither he, nor any other explorer, ever found the fabled inland sea. What Stuart couldn't have realised is that he was standing in an inland sea the whole time.

This area was once covered by the Larapintine Sea which bisected the vast Gondwanaland continent, a tropical sea teeming with life. In the late Cambrian to Ordovician periods, the shallow Larapintine Sea covered much of central Australia.

As you stand at GZ, observe the mountains around you on the horizon, including Central Mount Stuart to the north-west. Millions of years ago, volcanoes lifted and pushed, causing these mountain ranges which then eroded making way for the inland sea. Although shallow, the inland sea covered most of central Australia and was home to sea worms and jellyfish. Then the sea retreated and the mountains reappeared.

Today, the mountains are once again eroding and sea fossils are being exposed in the underlying rock providing scientists with insight into life in the ancient inland sea.

To log this cache, please answer the following questions:

1. Describe how the mountains were created?
2. When did the sea retreat?
3. Why do you think the inland sea disappeared?

Please send your answers via private message. Do not include them in your log. Please do not include photos of any signs in your log.

You do not have to wait for a response prior to logging. I will contact you if there are any problems with your answers.

Ref: Trilobites from the Middle Ordovician Stairway Sandstone, Amadeus Basin, central Australia, retrieved from https://www.researchgate.net/publication/256718740_Trilobites_from_the_Middle_Ordovician_Stairway_Sandstone_Amadeus_Basin_central_Australia on 17 April 2017