THE GEOLOGICAL TIMESCALE
There is, of course, nothing special about geological time. Someone once said that geological time is the same as normal time except that there’s more of it!
A geologist, on the other hand, studies the history of the Earth since its formation about 4,600 million years ago. To put this vast span of time into perspective, if we try to visualise 4,600 million years as 24 hours, the last 250,000 years of man’s existence would represent less than 5 seconds! When one attempts to grasp this enormous time span it becomes clear that sufficient time has elapsed for great changes to have taken place on Earth.
A timescale of the Ice Age
For a timescale of the last 2.6 million years (the Ice Age) in Britain CLICK HERE
An ice age is a period when the Earth's climate cools sufficiently to form ice caps at the poles and on mountain ranges. There have been at least five ice ages in the Earth’s past, one of these was the extreme cold period known as 'Snowball Earth' at the end of the Precambrian (see above).
We are currently living in what is known as the Quaternary Ice Age which started 2.6 million years ago. In Britain, there is evidence for great swings of climate within the present Ice Age. For example, in the last 500,000 years there have been four temperate stages at least as warm as today, separated by cold stages with arctic conditions.
The reasons for these climate variations are complex but are mostly caused by astronomical rhythms such as periodic changes to the Earth's orbit around the Sun.
