Salt water and Ice

We looked at how cold water sinks today. First we took a jar of water that had been sitting in the room for a while. Then we added a cube of ice. This floated on the top. Next we added some food colouring and the food colouring followed the icey water as it was melting in the jar.

We then tried the same thing again, this time with a jar of salty water. The ice sat on top again but when we added the food colouring, it just stayed on the surface - it wasnt as dense as the salt water so it didnt sink!

Ice formed in the Antarctic (and the Arctic) is fresh water. The salt in the water gets 'spat out' and sinks. The water below the ice is very salty.