Science corner

27th February 2004 at 00:00
Landscape design: make a topographic map with Sophie Duncan

This experiment is an extension of an old favourite - the reaction between baking powder and vinegar. Here, the important exploration is how landscapes develop and what they can tell us about the history of the area.

Using a tray, take a small plastic bottle and surround it with Plasticine to make a "mountain", ensuring that the bottle can be smoothly removed time after time. Add the ingredients for a volcano to the bottle (one tablespoon bicarbonate of soda mixed with food colouring and washing-up liquid). Add vinegar to make the volcano erupt, and allow the "lava" to flow over the mountain.

Take some differently coloured Plasticine and cover the areas where lava has flowed. Repeat the process a number of times to explore how it flows differently as the landscape changes.

Now use a straw to take core samples, which will show up the differently coloured layers to indicate different time periods.

You could make a topographic map of the mountain. Remove the bottle and fill in the hole with Plasticine. Make three holes by inserting a bamboo skewer as far as it will go vertically through the top of the mountain.

Mark the highest point of the mountain on the skewer and take it out, dividing its length into five equidistant points.

Starting from the top, use dental floss to cut a slice through the mountain at the first point marked on the skewer.

Remove the mountain slice and draw around it on paper, marking the three holes.

Repeat with the next section, lining up the holes as marked. Repeat this until you have five outlines drawn on the paper. Reform the mountain.

The outlines you've drawn are a topographic map of your mountain.

Sophie Duncan is project manager for science at the BBC

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