SOSP: OUR LIMESTONE LANDSCAPE
SOSP: Science on Salisbury Plain
It is the ‘hard’ water in South Wiltshire that leaves white, and sometimes costly deposits in our kettles and washing machines, and is largely due to calcium carbonates dissolved in the water – but why is so much calcium here?
Chemistry: Deposited during the Cretaceous Period (100 million years ago) calcium carbonates in the ground are a reminder of the warm, sub-tropical seas that once existed here. In those seas lived numerous bivalves, ammonites and echinoids (sea-urchins), a sea rich with animals with exoskeleton made from calcium carbonate. Echinoids in particular, seemed to find this area a great place to live, as we can see from their fossil remains in and around Salisbury Plain.
Scientists use fossils to work out what they looked like and their drawings bring them to life. you can try drawing a pre-historic creature by following this link.
Physics: The echinoids used a hydraulic system to fill soft tissue in their tube feet with water, allowing them to move. The amount of water was controlled by a type of valve called a madrepore. You can find out how to make your own hydraulic arm here.
Biology: Belonging to the family of echinoderms (meaning ‘spiny-skins’) echinoids are related to starfish. Prehistoric echinoids called Micraster had heart-shaped exoskeletons, made from plates of interlocking calcium carbonate, with their mouth at the bottom so they could feed from the ocean floor. You can still see this in their fossils today.
You can see how palaeontologists (fossil scientists) piece together fossils to find out more about early life on Earth and try it for yourself here!
Photograph: The Micraster fossils in this photograph were all found on Salisbury Plain. Next time you are out for a walk along chalky paths, where the ground is flinty, see if you can spot a little piece of pre-history – a fossil of a sub-tropical sea creature that once lived here!
Find out more about the prehistoric world with these fun activities https://www.amnh.org/explore/ology/paleontology
Catherine Wilson, Assistant Head (Professional Development), Teacher of Physics