Creswick's Thermal Lake and Dinosaurs! EarthCache

When you arrive at the coordinates you will think that you are looking at ordinary farmland.

After reading the display board you will be amazed at what was once here!

Volcanoes erupting and spewing lava, a thermal lake and on the shores of it dinosaurs roaming.

Now of course you can notice the volcanos are covered in grass, the lake is no more and of course there are no dinosaurs.

Volcanos     

The Western Victorian Volcanic Plains are the third largest volcanic plains in world. They  cover an area of 2.3 million hectares, more than 10% of the state.  The basalt plains were formed by volcanoes over the last 6 million years. More than 90% of the plains have been cleared for farming. Over 400 volcano sites have been found on the plains. Near Ballarat the volcanoes are quite close together. The plains have built up over time with many small lava flows, and the average depth of the lava is about 60 metres. As the plains are so flat, the features of the volcanos stand out.

Magma from the planet's mantle rises through the planet's crust, if the magma from the mantle reaches the planet's surface it behaves differently depending on the viscosity of the molten constituent rock. Viscous (thick) magma produces volcanoes characterised by explosive eruptions, while non-viscous (runny) magma produce volcanoes characterised by an effusive eruptions pouring large amounts of lava onto the surface. When the magma cools it crystallises and forms rocks, the type of rock formed depends on the chemical composition of the magma and how rapidly the magma cools. Magma that reaches the surface to become lava cools rapidly resulting in rocks with small crystals such as basalt

Fossils

Unfortunately the fossils that were found in this area have been removed and destroyed. The miners had no use for them and never bothered to preserve them. Most of the ones found here related to the lake and what was in and around it. You will learn more at the site.

OK on to the questions!

To log this EarthCache please send the answers to the following questions:
 

1. How many kilometres in diameter was the lake, and how was it formed?
2. Make a comment on the viscosity of the lava that erupted in this area and describe what observations have led you to this conclusion.
3.         What are the three main fossils the miners found? 
4.         When did the mine close?