£0.00View All
(0) Shopping Cart






The science of geology involves vast periods of time, known as ‘geological time’ or 'deep time' and this takes some getting used to. The concept was first developed by the Scottish geologist James Hutton in the 18th century who proved by pioneering fieldwork that the Earth was immensely old. One of Hutton's friends, on seeing a rock outcrop that Hutton had discovered, famously remarked "the mind seemed to grow giddy by looking so far into the abyss of time".

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!

The concept of 'Deep Time'
Geologists talk of millions of years in the same way that archaeologists talk of hundreds of years.  It is useful to compare geology and archaeology because the two sciences are often confused.  An archaeologist studies the history of mankind through the excavation of human remains and objects either made or fashioned by man. Usually this involves the last 250,000 years, for most of which man was using stone tools; it is only during the last 4,000 years or so that humans have been using metals.  
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.

Geological time is divided into periods just as English history is divided into periods such as Roman, Saxon, and Norman. These geological periods are subdivided into epochs and grouped together into eras. 

The geological timescale
A complete geological timescale is complex but a simplified version (not to scale) is given below: 

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.