Chiltern's Geology - April 29th 2015
Dennis Treble, secretary of the Pitstone museum, provided us with an interesting talk on the formation of the Chiltern Hills and some of the geological features that are so familiar in this area.
As a preamble he talked about the age of the Earth to illustrate how long rocks take to form. Many eminent scientists have put forward their theories of the age to contribute to the debate. Lord Kelvin, for example, based his theory on the rate of cooling of the planet and claimed that the Earth is 24 - 40 million years old. The modern theory is based on the rate of decay of radio activity in the rock. Most scientists now accept that the Earth is 4.5 billion years old, e.g. if we say that a year represents 4.5 billion years then man has lived on Earth for the last 1.5 seconds of December!
Dennis then went on to talk about the formation of different forms of chalk and flint. This chalk bed, which was at the bottom of an ancient sea, was uplifted to form the Chilterns and the North and South Downs. The clay of the London basin filled the depression and the Weald of Kent formed between the Downs. Since then ice and water have weathered, over many millions of years, the ranges to the soft rounded hills that we know today. The scarp slope and dry valleys are some of the chalk features that we see today.
As a preamble he talked about the age of the Earth to illustrate how long rocks take to form. Many eminent scientists have put forward their theories of the age to contribute to the debate. Lord Kelvin, for example, based his theory on the rate of cooling of the planet and claimed that the Earth is 24 - 40 million years old. The modern theory is based on the rate of decay of radio activity in the rock. Most scientists now accept that the Earth is 4.5 billion years old, e.g. if we say that a year represents 4.5 billion years then man has lived on Earth for the last 1.5 seconds of December!
Dennis then went on to talk about the formation of different forms of chalk and flint. This chalk bed, which was at the bottom of an ancient sea, was uplifted to form the Chilterns and the North and South Downs. The clay of the London basin filled the depression and the Weald of Kent formed between the Downs. Since then ice and water have weathered, over many millions of years, the ranges to the soft rounded hills that we know today. The scarp slope and dry valleys are some of the chalk features that we see today.