We know Aotearoa New Zealand is home to many geographically and biologically special features. Yet few of us know it also has its very own measure of “deep time”.

Known as the New Zealand Geological Timescale, it has just undergone its most comprehensive revision in 20 years.

Like the periodic table, the geological timescale brings order to Earth’s deep history, measuring millions of years of time recorded in the rocks beneath our planet’s cities and towns, mountains and rivers.

It has been described by American writer Marcia Bjornerud as “one of the great intellectual achievements of humanity”.

For more than a century, New Zealand geologists and palaeontologists have maintained their own scale because the international timescale, developed largely in Europe and North America, has been difficult to apply elsewhere.

Even today, most boundaries in deep time are defined using fossils. Most New Zealand fossils, as with our living plants and animals, are found nowhere else.

The revised New Zealand version updates the ages of the timescale’s divisions and removes many long-standing ambiguities in how they are defined.

As a result, it will improve our understanding of both the geological gifts and the geohazards of life on the “shaky isles”.

Looking beyond the human timescale

In one sense, deep time is the antithesis of the short-term view that drives political and economic cycles.

To properly understand climate........

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