It’s true that time moves faster the older we get. Although we’re not quite sure why. One hypothesis states the rate we process visual information slows down as we get older, giving us the illusion time is speeding up. This is a bit confusing because time is a created construct. As we evolved this construct has become engrained in our minds. Think of how differently Monday through Friday looked for a hunter gatherer compared to today. Most of us spend the bulk of those hours working, commuting and sleeping with little free time to interact with people we actually want to see. As we move through life and watch loved ones pass on, the finite nature of our time becomes increasingly apparent. Our bodies begin to ache a little more and wrinkles start to appear, we are slowly breaking down. Time is slipping away.

I once read an article about a successful businessman whom in his final moments realized how much of his life he had wasted. Spending years building a career which yielded him insurmountable success, all of which he didn’t realize until the very end, meant nothing. In a few months, the colleagues he spent countless hours working with would move on, finding someone to fill in his place. The success he achieved would be remembered by some but mostly fade away becoming a distant memory. Relationships and memories with the ones he loved are what truly mattered. People often recount others as whom they were as a person, not all that they achieved. I’m sure many others have felt the same in their final moments. I’ve lived with regret at moments in my life. Sometimes I fall into a dark place and feel regretful about choices or decisions I made. However, I always come out on the other end of that dark hole realizing life has only continued to move on since that choice. Life will continue to move on regardless of the choices I make, the feelings I have, my successes and failures. In fact, life has always moved on no matter what has happened. If time is a created construct, how we chose to perceive it is an individual choice. Thinking about time in relation to the Earth, the hours and minutes don’t seem to matter as much when the scale is billions of years. Although we have changed this planet more than any species before us, we are no different from the antelope being chased by the cheetah or the koala bear that spends its days chomping on eucalyptus. The geologic time scale has made that very apparent.    

Junior year of college was the first time I learned the Earth was 4.56 billion years old. I couldn’t wrap my mind around that number at first, in fact, even today it is still difficult to grasp. The geologic time scale at first glance is this large vibrant colored chart with four rectangular blocks representing the four major eras; Precambrian, Paleozoic, Mesozoic and Cenozoic. Each block breaks down into a series of long columns increasing the level of specificity in time the farther right you travel from periods to epochs to ages. Running parallel to these columns is a time scale in the magnitude of millions of years, arranging the blocks from youngest to oldest. If we were to put Earth’s history into a calendar year the very basic life forms like algae wouldn’t appear until March, Dinosaurs on Christmas and Homo Sapiens a mere 12 seconds before the ball dropped.

The first time scale was developed in the 1800s using relative ages based on the law of superposition. When examining an undisturbed stack of rock layers, or strata, the youngest will always be on top and oldest on bottom. At the time there was no way of putting dates to these layers, but scientists were able to use fossils found in strata to determine which species coexisted and a relative idea of their evolution. In the 1900s scientist were able to determine absolute ages of rock layers through advancements in radiometric methods. Certain isotopes within elements are unstable, or radioactive, and lose energy over time. This process is referred to as decay and involves shedding of one or more subatomic particles within the isotope at a constant rate until the element is stable. Radiometric age is thus determined by comparing the amount of radioactive versus stable isotopes in the rock or mineral. The time scale is continuously being updated and debated as dating methods improve, increasing the level of specificity and accuracy. Geochronologists specialize in dating geologic ages and can now distinguish events that happened tens of millions of years ago within a few thousand years of specificity.  

One of the many beauties about studying Earth is that the story is never over. Geologist have proposed adding a new period to the time scale, about 10,000 years ago to represent when humans began to alter Earth. Tentatively referring to it as the Anthropocene, characterized as geologic layers of plastics, petrified food waste, old tires, discarded cellphones, construction debris and millions of miles of pavement. In my opinion the Anthropocene will be the saddest layer in Earth’s history, even when compared to the five mass extinctions. Earth is going to survive regardless of what we do to it, so it is not really the planet we are trying to save but ourselves. There are those who are fighting to stop what now seems to be the inevitable, climate change, then others who see the writing on the wall and are searching for a new home.

We have been so lucky in the past few thousand years to live in near perfect conditions, disconnecting us from reality. Creating our own pristine bubbles, slowly taking over the places we once roamed, shaping us into entirely different beings. Studying the time scale has taught me that on Earth nothing remains perfect for very long. This giant rock is constantly changing, never taking into account its inhabitants. I’ve found the more I learn about the Earth, the more I love and appreciate all that it provides us. Over the next series of posts I’m going to delve into each geologic time period, in hopes of getting at least one person to connect with the globe through learning as I have. Starting with the oldest, in true geologic fashion.

Stay tuned friends!


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