Geologic time

How do I count time? I thought my four years of high school was a long time. Most of us don’t live beyond 85 or 90 years. Whole civilizations come and go in the order of one or two thousand years. A million years is a thousand of those thousands. over the period of roughly 250 to 60 million years ago ocean floor was being sucked under the western edge of North America, bringing sediments with it and pasting whole volcanic island chains onto the continent. Sideways pressure from this movement folded these rocks into folds trending roughly parallel to the continental edge. Rivers carved their channels along these folds, trending roughly NNW-SSE.

As more subducted ocean floor and sediments went down, they heated, melted and formed great bodies of molten rock which gradually cooled and crystallized far below the surface. These now form the granite batholith of the Sierra Nevada and other related ranges.

Since that time the Sierra has been uplifted so much that streams have made new courses down the west-sloping surface of these massive granitic rocks. However, in places, remnants of the old NNW-SSE stream patterns persist on or near the remains of the old wall rock.

Such a drainage remnant is the trough extending from Parker Pass on the eastern boundary of Yosemite National Park northward across Tioga Pass and through Saddlebag Lake east of the crest. Most but not all of this trough is still in the ancient sediments and volcanics, now tilted at high angles. Mineral deposits in these rocks attracted miners who established the mining camp of Bennettville.

My buddy and I walked through these mountains, touched their rocks and marveled at the beauty of their trees, meadows and flowers.

This is our heritage locally from “only” the last quarter of a billion years. Earth’s and the Solar System’s age has been estimated at about 4.54 to 4.6 billion years . The best estimate of the age of the universe as we know it is c. 13.7 billion years.

Now to size: Despite the vast distances between the elements of our Solar System, we then have to account for the even more vast distances between stars in our own Milky Way Galaxy. Then there are the distances between galaxies…and on and on. Here’s what one author says about attempts to guage the size of the observable universe

What it all boils down to is that each one of us is immersed in an unimaginably grand unity of time and space–this is our heritage and environment of which we are full members, and time keeps rolling forward. Makes me both humble and aware that as such, I’ve got inestimable worth as part of this grand whole–as have each one of us.



About David McCoard

After earning my MS in geology I've done various things including managing the ski touring program at a small lodge in the Sierra. In 2010 I retired from Contra Costa College in California. I've always been fascinated by the mountains and nature and have spent countless days hiking, backpacking, climbing and skiing in the Sierra. The spiritual insights I've learned there have set the course for my life. Now I have time to share them and strike up a conversation.
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One Response to Geologic time

  1. Krista Farey says:

    Beautiful piece. Thanks, Dave.

    Love, Krista.

    Sent from my iPad


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