Why do a chronology of major events in the Earth's history? Many timelines concerning the history of civilisation, including dates of battles and rulers, have been published, as have many good academic and reference books on changes in global climate, migration of land masses and so on. There is also much useful and thought-provoking material on the Web.

What interests me, however, is the vast expanse of time, BC, in which the recording of important events is patchy and increasingly elusive the further back one searches : a field of play where scientists, pseudoscientists and proponents of religious dogma enthusiastically and sometimes intolerantly vie to convince the world at large (and sometimes themselves) of their pet theory. Taken at face value the theory can be persuasive, but where dates are involved, how does it stack up against existing evidence and the arguments of others?

Where do the various myths and legends of prehistory fit in ? Could putting all the dates together in context give a new twist to the history of civilisation or pre-history?

The Bible alludes to actual historical events and leaders as well as being a vehicle for myth, prophecy, poetry and moral authority. For example, Noah' s Flood, which various scholars have attempted to date: was it truly global, or more of a regional - nonetheless devastating - event for the Middle Eastern chroniclers? A similar event features in other non Judeo-Christian traditions. Did they coincide with the disappearance of Atlantis?

Global warming is very much on our minds at present, but historical, geographical and biological evidence prove that the climate of Europe has been even warmer before. Are there parallels between dramatic climate change and mass extinctions?

It is no longer assumed the Earth has remained unchanged for millions of years. The biosphere is vulnerable because Earth is still geologically active ; there are cycles of change within the Solar System, and unpredictable threats from asteroids, comets and meteorites remain. Some of these have left their mark on Earth history, from the fossil record to the the era of human civilisation.

This chronology records events which generally indicate that the Earth is much older than ancient peoples believed. Where is the evidence for this, and are the dating methods consistent? Well, the passage of the years and seasons are recorded in nature - in everything from stalactite growth layers, to ice cores, to pollen remains, to lake and sea deposition sediments. All are available to reveal that there have been tens of thousands of years of history beyond the limited range of tree ring dating (dendrochronology).