Mike Tuke’s

Plants Samples D Students are shown modern examples of plants which are found as fossils e.g. a frond of Dawn Redwood, (metasequoia glyptostroboides, common in gardens), a Horsetail, common in damp places and photos of modern tree ferns from New Zealand. Carbonisation D Surround a leaf with clay and heat it in the oven.  Break it open. Trunk diameter   I  5 min Because Carboniferous trees were hollow they are often squashed flat. Students measure the width (w) of a squashed fossil trunk and calculate what its original diameter (d) was.  d = 2xw/∏ Bamboo  D Carboniferous trees were rather like bamboo, hollow inside. However bamboo is a grass. Strength of trees Pa I 15 min Compare the strength of Lepidodendron which was hollow inside and that of Oak which is solid.  Resistance to bending is proportional to Young’s modulus for wood x second moment of area                                 length If the properties of the wood are the same and the length (tree height) is constant then the only variable is the second moment of area. This is Π/4 x r⁴ for a solid tree and ∏/4 x (r¹ – r²)⁴ for the hollow tree, where r = radius, r¹ = outside radius and r² = inside radius. After the Ice Age Pa I 5 min Students are given a diagram showing the abundance of each type of tree pollen found in clays deposited since the Ice Age.  They must work and explain out the order of arrival of the different types of tree.

Earth Science Activities and Demonstrations