By SANDRA RENDGEN
The Earth is roughly four and a half billion years old. For most of that time, our planet’s geological and biological development was unbelievably slow. Then things got moving …
How can we possibly form even the faintest idea of the unimaginable process that is the history of the Earth? Of how it evolved from a body of molten rock into a planet with continents, an atmosphere, a population of seven and a half billion people and a climate problem? I have always been fascinated by this intellectual challenge. Not only is its development overwhelmingly complex to comprehend, but the timescale over which it has happened is monstrous.
Published in 1975 by the United States Geological Survey, “The Geologic Time Spiral. A Path to the Past” is part of their general interest publication series. The scientific authority – which researches geology, climate and environmental issues – routinely hands out maps, writings and other documentation to inform the public, but this one has been particularly enduring. In creating a compelling – if condensed – visual history of our planet, it provides a glimpse of the inconceivable, sheds some light on the unimaginable. It’s in executions such as these that infographics prove their inherent potential as a tool for fostering insight.
What a visionary abstraction! With geological time represented as a narrow plateau, spiralling back into the depths of history, we are shown geological and biological processes unfolding, the historical epochs labelled along the sides. At the front end of the spiral in the lower centre of the graphic, we see our present epoch, a tiny sliver representing the past 11,500 years (more than 140 lifetimes).
To put this ingenious graphic invention into context, take a look at this standard geological time scale (below), based on rock strata research. While most layers of this column look pretty equal through all eras, time stamps correct this picture. The short column on the right, shaded in pink tones, represents the four billion years of the Precambrium (the first 88% of Earth’s history). In contrast, the column on the left, in greenish/yellowish shades, represents just 3% of the planet’s history – the past 145 million years.
It was only with the beginning of the Cambrium, around 541 million years ago, that an enormous amount of animal species evolved and a variety of lifeforms exploded on this planet. The time spiral deals with this focus by having the Precambrian era corkscrew elegantly away to dust, imparting a sense of its inconceivable duration without the need to spell it out in much detail.
The periods since the Cambrian epoch, on the other hand, are displayed very eloquently, almost like in a children’s panorama. See the little arthropods climbing up the spiral in the Cambrian period. Look at the variety of dinosaurs and rich wildlife wandering the terrain throughout the Mesozoic Era. Along the edges, mountains evolve, volcanos spit out ashes and dust, plants pop out to form lush habitats.
Of course, this imaginative piece was always intended to be a popular explanation. Other than the stratigraphic chart above –which was designed as a means of communicating scientific data, and is regularly updated as new research is published – this poster is meant to fire the imagination of readers who are not paleontologists or experts of historical geology, and who are not familiar with the succession of eras in the history of Earth. However, this piece has managed to create such a convincing image of our planet’s past, that today – 45 years after it was designed – it is still circulating widely and is used on many a website, including some major Wikipedia sites on the topic. Not bad for a popular poster, is it?
Sandra Rendgen is the author of two bestselling books on data visualisation and infographics, both published by Taschen. Currently she is getting lost in the history of data visualisation.