The Geological Column Map

A Four Dimensional Geological Map

A map showing length, breadth, height and time.

 m. y. = million years.

The Local Block Map has been put on top of the Geological Column, to take the story back more than 200 million years. Since that time, London has been a desert, it has been under shallow topical seas, under deep seas, and in many varieties of river conditions. These different climatic conditions laid down their different sediments to produce the different stones just as they are still doing today. This Geological Column reaches down to the Old Red Sandstone. Today Sheffield starts at the Old Red Sandstone.

In Sheffieldthe modern ground level starts at the old Red Sandstone. everything later must have been swept awar, or has been swept away.

A New Time Scale

Little has changed geologically since the Romans arrived here, apart from the mining of the area for gravel, the introduction of stones for building, and the creation of roads. Geologically there has not been time for much to change, although the existing geology has been considerably rearranged by human beings. It is extremely difficult to imagine the enormous lengths of time required for geological change, but let us try.
Let us invent a new unit of time - a "Caesar".

1 Caesar = about 2,000 years - the time from his landing to today.

Then from today back to the Old Red Sandstone Period is MORE THAN 100,000 CAESARS. Imagine dividing the height of this geological column into 100,000 parts. The time back to the Romans would be about the thickness of a piece of tissue paper.

Or think of it in another way. Caesar has two syllables. So has Second.

Repeat the word Caesar' every second for a minute. Assume that each second you go back 2,000 years. In 60 seconds you are back 120,000 years. To get back to the Old Red Sandstone, 213 million years ago, one would have to repeat the word Caesar every second for over 30 hours. A day and a quarter at 2000 years a second.

Lastly, the Old Red Sandstone is at the bottom of our London geological column, but it is at the top in Sheffield. Draw the Sheffield column and the story can be taken back millions of years further still.

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Updated: August 16, 2011