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Straight To The Core

Core samples are taken from a planet’s surface to provide information about the past.

Australian Curriculum links

  • Science > Earth and Space Sciences > Year 4 > ACSSU075
  • Science > Earth and Space Sciences > Year 8 > ACSSU153

You'll need

  • A packet of “Celebrations” or similar variety pack of chocolates
  • Clear plastic straws
  • Knife
  • Hot water
  • Ruler

Try this

  1. Pick a chocolate piece from the selection and unwrap it. Don’t eat it yet!
  2. Slowly and steadily “’drill” your clear plastic straw into the chocolate. You may need to warm the straw in some hot water to help itpass through
  3. Remove the straw and analyse the core sample, recording the thickness of each layer, its colour and texture. Are there any repeated layers?
  4. Use the knife to cut the chocolate in two, so the layers can be viewed more easily. Did your initial observation match what you see now?

Further investigation

Take a sample of each of the chocolate varieties in the packet. These are the known samples. With students working in partners, have them take a core sample and hand it to their partner. The partner should then try and identify this unknown sample using the known samples. Scientists use known samples to help them identify unknowns in many situations

Is one core sample indicative of the whole chocolate? Try sampling in different spots along the small bar. Do the cores look different? Do you think this would happen when taking cores from earth or other materials?

Using different materials

Chocolates may not work for all classrooms, so here are some different suggestions. You may want to use a larger sampling tool, like an apple corer, for some of these:

  • Try baking some different coloured cakes (chocolate, vanilla, red velvet), slice them into thin layers and core these lovely layer cakes. You may want to use a
  • Try stacking flat sheets of different coloured plasticine
  • Try different types of soils. Pick up a few samples from different areas and layer them on top of each other
  • Try creating your own ice layers by freezing water over a few days. Make a layer of water, freeze it, add another layer or water, freeze it and repeat until you have a series of layers. Take a core sample using a warmed apple corer.

What’s happening?

Core samples are a cylindrical section of natural substance, taken from the surface of an area using a special drill. A core sample can show the location of useful products (coal or oil); when ice ages, tsunamis and earthquakes occurred; the type of animals that lived in the past or what gas levels were like thousands of years ago. The layers build up over time, with the most recent layers deposited on the surface.

Real world links

Coring started in mining and exploration as a way to sample ore deposits and for oil exploration. This has now developed into many different areas. Some examples of core samples used by scientists for research include:

  • Ice cores, which are regularly drilled from Antarctica or the arctic. In a real ice core there are thousands of bands – each one representing a summer and winter snow fall of previous years. Once an ice core is obtained, tiny air bubbles inside it examined, some of which have been trapped in the ice for hundreds of thousands of years. Ice cores from Antarctica show us that the amounts of carbon dioxide and methane currently in our atmosphere are the highest recorded in 650 000 years.
  • Soil cores, which are taken whenever someone needs to look at the properties and types of soil in an area. To make recommendations based on soil quality, engineers drill small-diameter boreholes into the ground to collect soil samples. Soil is removed from boreholes in long clear tubes called soil cores. Soil cores permit engineers to examine many feet of the below-ground soil profile. Engineers use the soil cores to characterize the soil profile using borehole logs. They also take soil samples and further analyze them for characteristics, quality, water content, and pollutant or pesticide contamination.