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A Dive into Deep Time

The concept of deep time helps us understand processes that can last billions of years.

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Erosion takes eons to shape landscapes. Deep time encourages us to think on a scale large enough to imagine the forces at work.


The universe operates on such an enormous scale that it can be hard for us tiny, recently-evolved humans to understand the slow changes that created our world. After all, our lives are usually less than a hundred trips around the Sun, so imagining a process that lasts a billion years is no easy feat.

The 18th-century geologist James Hutton was probably the first to suggest that in order to grasp the scope of Earth’s 4.5 billion years of history, we need to reset our minds to think beyond our usual scale of hours or days, and imagine spans of millions of years.

Later, Charles Darwin expanded on this idea, revealing that the story of life on Earth was not a tale of a single moment of divine creation, but a saga of slow changes and evolution over vast expanses of time.

Still a Mental Challenge

Even in modern times, it is a leap of faith to believe that human beings can really wrap their minds around deep time processes that take millions of years.

The writer John McPhee, who popularized the deep time concept in the 1980s, pointed out how this runs counter to our natural way of thinking. In his seminal book Basin and Range, he wrote: "The human consciousness may have begun to leap and boil some sunny day in the Pleistocene, but the race by and large has retained the essence of its animal sense of time."

"People think in five generations—two ahead, two behind—with heavy concentration on the one in the middle".

Old man holding a baby

Grandfather and grandchild: Our personal experience usually encompasses just a few generations, but the concept of deep time encourages us to take a longer view.

©iStockphoto.com/Fly View Productions

Understanding the Past, Seeing the Future

But opening our minds to think beyond just a few generations and starting to picture our place in history on a deep time scale may help us plan for a better future.

On a personal level, you may know a lot about your family’s lives going back a generation or two. Deep time thinking would encourage you to take a longer view, and help you realize that you have four grandparents, eight great-grandparents, sixteen great-great-grandparents, and on and on. In the end, it's surprising to do the math and see that, if you go back 20 generations, you have more than a million ancestors.

And looking forward in time, it’s amazing to think that the baby you cuddle today stands an excellent chance of living to see the year 2100, and his or her grandchildren the first day of 2200.

A Tool for Policy

Governments are starting to employ an understanding of deep time as they wrestle with the long-term consequences of modern human activity—for example, for Earth’s climate: According to recent models, the heating of the planet through man-caused climate change has probably pushed back the onset of the next ice age by at least 100,000 years. So it has become clear that the last 150 years of our greenhouse gas emissions will have an effect on the environment of many generations of our descendants.

Policymakers in different countries have proposed legislation designed to shift the mindset of government towards a longer-term view that takes the interest of our descendants into account. One good example is Wales, where the legislature passed the Well-being of Future Generations Act in 2015.

In an interview with the BBC, Sophie Howe, the Future Generations Commissioner for Wales, highlighted how the law will affect decisions across the board: “It applies to all of our public services. Health boards, local authorities, national bodies, and really significantly, the Welsh government themselves have to demonstrate how they are taking decisions which meet today’s needs without compromising the ability of future generations to meet their needs.”