Buckden - a Huntingdonshire Village

WHY IS BUCKDEN HERE? 81 CHAPTER 1/ WHY IS BUCKDEN HERE? David Thomas The answer, says the author, can be summed up simply enough: ice and water. ow far back into pre-history do we want to go? Would one hundred and forty million years be enough? At that time the site of Buckden was under a shallow tropical sea, in which plesiosaurs and other ancient creatures swam. The seabed was made up of clay washed down from the lands nearby and the carcasses of the sea animals. Since then it has drifted northward, until it arrived at the latitude it is in today. Between two and a half and one million years ago, the earth became much colder with the advent of the current ice age. 1 Not all of the glacials resulted in ice covering the whole of Great Britain, but there was a time when what is now Huntingdonshire was under a thick layer of slowly moving ice. As it crawled over the underlying surface, the ice ground away the rock and transported it elsewhere, depositing the detritus when it melted in a warmer environment. The melting proceeded fastest on the higher ground. As the ice thinned and the darker layers underneath gained more heat from the sun, so stones, sand, clay and other mineral particles were often left on the tops of hills. This is where we now find the stony clay soils known as boulder clay or glacial drift. At the same time, the valleys were carrying away the melt-water of the glaciers in huge quantities. The speed of the glacial rivers was such that the finer parts of any rocks were carried out to the ever-rising seas, leaving behind the coarser as sands and gravels. The melting of the glaciers did not take place at a steady rate. Several times the cold returned, increasing the depth of ice again. As a result, the hilltop clays and valley gravels received new deposit layers, which differed from those above and below them. These are mainly of interest to geologists, however, and do not affect the story of humans on the land. It was the action of ice and water, then, which left Buckden with the shape of the land as it is now: gently sloping hills to the west and the shallow valley of the river Great Ouse to the east. The boulder clay and gravel has a substratum of blue-grey Oxford clay. This clay was laid down under the sea, and is the source of the fossils that sometimes turn up in our soil, such as Gryphaea (fossil oysters informally known as the devil’s toenails) and dart-shaped belemnites, the internal shells of extinct relatives of the squid and cuttlefish. Rainwater can slowly penetrate the boulder clay until it reaches the Oxford clay, but this is 1 An ice age is a cyclical epoch during which a significant area of the earth’s surface remains covered with a permanent ice sheet (as Antarctica still is today), while other large sheets advance and retreat, expanding during very cold periods (known as glacials), but starting to disappear during milder ones (interglacials). H