The deep present

A little geology knowledge can be transforming, and a lot can put you in weird territory. But it doesn’t feel so weird to me. You’ve heard of geologic time, the Earth’s lifespan, an ocean of time so deep — billions of years — that it’s unfathomable. I’ve lived in deep time for decades. I look at the past in a totally different way than most people. And I also see the present in deep focus. Let me tell you about the geological present — the deep present.

The landscape evolves so slowly that we can confidently say it’s looked just the same since tens of thousands of years ago. Those hills, those streams and those rocks have been sitting there all that time. The landscape has seen it all. The deep present is the “today” the landscape feels. Anything that’s happened in that time span is just part of the day’s events.

For instance, maximum-size earthquakes on the Hayward fault occur every few centuries. No one alive has witnessed one, but in the deep present, they’re as routine as rainy winters. The landscape is used to them.

In humans, the deep present is a peculiar detachment that lets us see rare but geologically routine events as a factor in the present day. It lets us not just see, but feel the constant possibility of world-changing events.

As I put it to writer Lucy Kang a few years ago, “The deep present is the awareness that what’s around us today is a snapshot that superimposes many thousands of years of history onto this moment. Anything in the geological record that’s happened since the glaciers left — giant quakes, thousand-year floods, centuries-long droughts ­– could happen again tomorrow.” It’s a little distressing that record-breaking floods and droughts have both happened since I wrote that; fortunately, a giant quake has not!

What most people might think of as dead ground — hills and rocks — I see as alive, geologically alive: material responding to energy. Geology is very slow until big things happen suddenly. Rivers flow gently, but one week out of ten thousand they rise up and wipe out their surroundings. And when that one week is preserved in a rock like sandstone or shale, it might be a layer of sand, washed far out to sea, a centimeter thick. The other ten thousand weeks amount to an even thinner layer of clay.

Now picture whole cliffs of such rocks, kilometers in thickness, made up of those little layers and nothing else. That’s deep time.

The events of deep time are irretrievably condensed and blurred; they’ll never be revealed in the clarity and detail with which we see today. But being able to see the present day as an age, rather than a moment, gives us new and valuable insight.

Today is seductive. As we think of our surroundings, we tend to favor the good days over the bad. The river is well-behaved so much of the time that the possibility of a hundred-year or thousand-year flood seems distant. The “big one” earthquake lasts just a minute or two, while the centuries in between are placid and prosperous. Volcanic eruptions can wipe out everything around, but they happen so seldom.

As individuals, most of us enjoy the good times and place our bets on the odds that we’ll be OK. Cities, states and civilizations cannot place such bets, not if they plan to endure. They help ensure, through laws and institutions, that they will last for generations. Today there are demands for civilization to do even better, to become more nearly sustainable: closer to eternal. Geology is essential for reaching that goal.

Even the deep present can be seductive. We know that since the end of the last ice age, about 12,000 years ago, the Earth’s climate has been warm and steady, in comparison to other times in the deeper past. “Geological today” has been a nice day. The global warming that’s now well under way is pushing the planet beyond that comfortable state.

Physical evidence of the geological past can give regions a good sense of their typical range of conditions on the thousand-year scale: their deep present. With that knowledge, planners can design realistically based on deep history rather than hopefully, based on today’s nice weather. And the more citizens and their leaders who share the geologist’s sense of the deep present, the better equipped we’ll be to face the deep future. It may not be enough, if the Earth wanders off the relative stability of the last 12,000 years, but it might suffice if we start today.

This piece is partially adapted from one I wrote in 2012 that the publisher has erased.

4 Responses to “The deep present”

  1. Melodie Says:

    It is true that Co2 levels didn’t start breaking out of the ordinary cycle until 70 years ago, but previous highs fit a normal-ish cycle.

    So, I agree that there is more to warming than just co2, but the levels have gone into unknown territory by virtue of being so high, and will quite possibly make it impossible for us to determine other factors that contribute simply because the co2 is so extreme.

    For purely personal reasons,
    I’m kind of glad I don’t have grandchildren. Looking at the co2 graph over the last couple thousand years is actually terrifying.

  2. jlippsberkeleyedu Says:

    Michael: Milankovitch cycling causing the earth’s axis to change dimensions, the tilt to change, and precession to cause the equinoxes to change position on the orbit. These factors, each operating at different time scales, cause increases or decreases in solar insolation that then influence the climate, oceanography, and glaciology of Earth. Warmer times = higher sea level; cooler times = lower sea levels. As climate (and the oceans) warmed after the 13,000 sea level lows of around 400 feet, collapsing and melting ice sheets and glaciers created rising seas worldwide. See Jere

  3. Melodie Says:

    I have always seen the landscape as an alive and moving thing, but I always wondered why until I started reading up on our local geology (and geology in general), and now it makes much more sense!

    Sometimes, though, I kind of wish it didn’t, because it has made me much more aware that it could change in an instant. Especially here …

  4. Michael Says:

    Interestingly, 20,000 years ago, sea levels were 120m lower than today. This allowed the first Americans to walk over from Asia … once they had exterminated their greatest predator, the short face bear. I often try to picture the bay with sea levels 400′ lower than today.

    On climate change, if you look at the NOAA data for San Francisco, which dates back to 1853, sea level rise begins in 1863, marking the end of the little ice age. Curiously sea level rise predates co2 rise by 87 years.

    Also curiously since sea levels were 120,000mm lower 20,000 years ago, we can easily see the simple average sea level rise is 6mm/yr. But NOAA sea level data going back 170 years has an average rise of 3mm/yr.

    Since we know co2 has remained steady from 20,000 years ago until 70 years ago, what then caused 6mm/yr of sea level rise with lower co2, but only 3mm/yr rise with unprecedented increasing co2 rise?

    I do think there is much more to climate than co2.

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