Volcanoes and plates

Lava is a mixture of melted rock, minerals and gases, and it is far hotter than anything in a kitchen. Not all lava behaves in the same way. Runny lava flows quickly and can travel a long way. Thick lava flows slowly and piles up near the opening, and over many years the hardened rock builds the cone shape we often see on volcanoes. Some very thick mixtures hardly move at all and harden inside the volcano. The steepness of the ground matters too: lava runs faster down a steep side. Volcanologists map lava flows to keep people safe. To study the idea without any danger, we use a model: cold flour paste on a tilted tray. A model is much smaller, cold and harmless, but it shows the same pattern, that thin liquids flow farther and steeper slopes make faster flows.