The South Downs is a one hundred mile long ridge of chalk laid down in the cretaceous period. Chalk is the remains of single celled creatures that drifted through the oceans around 140 to 66 million years ago. It makes up most of south east England and is a relatively young rock, but travel north and west and the geology of the UK gets much older. The science of geology deals with these huge time spans by creating aeons, eras, periods and epochs. But geology is not static. Change is everywhere. The world is not made up of things, only processes.