A fascinating geology display will be formally unveiled at the Railway Land Festival in Lewes on Sunday July 5 by Professor Rory Mortimore.
The display will feature drilling cores, fossils and drone shots while QR code triggered videos set out long term historical climate change.
The chalk in the South Downs reveals a time when Earth was a ‘hot-house’ with no or little polar ice.
But it also shows there were small cycles of temperature and climate change, represented by the alternating beds of marl-limestone in Southerham Grey Pit.
Professor Mortimore, who will open the exhibition said: “Climate and sea levels have constantly changed throughout geological time.
“The rocks that make the South Downs record nearly 40 million years of environmental change.
“Sea-level was 300 metres above present day, two times the height of Beachy Head, when the chalk, exposed in the river-cliffs at Lewes opposite the Linklater Pavilion, formed.
“The animals that lived in that sea and on the seafloor are the fossils that we now find in our local chalk pits and shown in these displays.”
Chalk is formed from lime mud, which accumulates on the sea floor in the right conditions.
This is transformed into rock as sediment builds up on top.
Lime mud is subjected to heat and pressure which removes the water and compacts the sediment into rock, while lime mud is formed from the skeletons of plankton.
The free Railway Land Live! Festival, supported by the Heritage Lottery Fund, will include a Minecraft game based on the Reserve, underwater wildlife images and a puppet show, as well as displays by the young sea level rise group the Linklater Rats.
There will also be live music and refreshments. It runs from 2pm-5pm at the Railway Land Local Nature Reserve, situated at the end of Railway Lane.