Archean To N E O P Ro T Er O Z O I C

The second half or 'leg' of our journey through Earth Time takes us across the Atlantic and the North American continent to one of the world's most spectacular natural phenomena - the Grand Canyon. Here in a single river gorge we have a vertical section through some 1.7 billion years of Earth Time. We follow in the footsteps of pioneer geologists such as John Wesley Powell as they explored and mapped the Canyon's strata. The rocks revealed a peculiarly North American slant on the Earth Time story.

Some episodes, such as the vast expanse of the Precambrian, are revealed in much greater detail, while others, such as the Jurassic and Cretaceous, are missing altogether. Indeed, if Earth Time had been originally carved up according to the Canyon's rock record, its subdivisions would have been significantly different from those recognised in the European testimony of the rocks. But together the two lines of section complement one another. From such varying regional accounts of Earth Time geologists have had to find ways of recognising and matching contemporary deposits around the world. As a result, they have had to adjust the internationally accepted subdivision of Earth Time accordingly.

Our journey through the Canyon's strata follows Powell and begins in the oldest rocks at the bottom of the chasm and climbs up through younger and younger strata - a reverse chronology to our exploration of Smith's section.

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