Why Does Some Lava Move Fast and Some Crawl?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why does some lava move fast and some crawl?

The Big Idea

Lava speed depends on how runny it is! Runny lava can race downhill, while thick lava barely creeps. Scientists call this stickiness viscosity.

Runny Lava

Step one: runny lava. Lava with little silica, a glassy ingredient in rock, is runny like thin syrup and flows easily. On a steep slope it can speed along as fast as a person jogs.

Thick Lava

Step two: thick lava. Lava with lots of silica is thick like toothpaste. It piles up and barely creeps, sometimes only a few meters a day.

Hot or Cool

Step three: temperature matters. Hotter lava flows more easily, just like warm honey pours better than cold honey. As lava cools, it gets stiffer and slows down.

A Closer Look

Let's take a closer look! Water is runny and races down fast. Cooking oil is a little slower. Honey is thick and slow. Cold honey is even slower, just like cooler lava.

Quick Facts

Quick facts! Viscosity is a word for how thick or sticky a liquid is. Silica is a main ingredient of many rocks, including sand and glass. Basalt lava is usually runny. Lava that is rich in silica can be very thick.

Think Like a Scientist

Now, think like a scientist! Tilt a tray and race drops of water, oil, and honey down it. Which is fastest, and which is slowest? Take a guess first. Then put the honey in the fridge for a while and race it again. Ask a grown-up to help with the tray.

Outro

Runny lava races, thick lava creeps, and hotter lava flows easier. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!