A Lot on Your Plate

I boarded the plane giving not a thought to how easily I can flit above the surface of the earth like a bird or maybe a dragonfly. This time my flight to Phoenix took an unusual route. Generally we fly over Las Vegas, but this day there was heavy weather in that area so we continued south from San Jose straight down I-5 to the Grapevine. From my window seat on the west side of the plane I could clearly see the “new” mountains that separate the San Joaquin Valley from the Salinas Valley and on the horizon the even newer mountains of Big Sur with the Pacific beyond.

New mountains, I say, because suddenly my mind jumped to an earlier era before the mountains, before there was the land that was now beneath me, a time when I would be flying over open ocean. This was the era when the stable land I grew up in—the old land of Iowa and the Midwest—was the continent, and this was a sloping ocean shelf collecting the marine deposits of millennia.

Through the mountains at the ocean’s edge, I could picture the Pacific Plate slowly subducting, slipping north and east, down under the North American Plate, its dive under the continent scraping off its top layer, piling up mountains like those of the Coast Range and Big Sur. In the middle of the Pacific I could envision the ocean floor as it slowly spread out, out, out, new crust welling up from deep within the core of the earth pushing the land up into the shape we call California.

The forces at work here challenged my imagination. The pulse of the earth pushes on twenty odd plates that comprise the surface of the earth. At weak spots or faults, like the one east of the Sierras, the push of plate on plate tilts up mountain ranges like a child might push up a ridge in a piece of paper. The Sierras are slowly being pushed up and up from underneath at a rate even faster than they are being brought down from above by the forces of wind and water.

The San Joaquin Valley remains a remnant of the ocean floor that has risen without a wrinkle between the jumbled geology of the Sierra tilt and the Big Sur scrape. What magnificent chaos!

Only in the last three decades have we begun to understand a little of what is happening here. The knowledge of plate tectonics has coalesced into a science now embraced—and, of course, disputed—by the academic community. How incredible it is that we now use rebounding waves of energy to look at the image of an unborn child and to infer the image of an unborn continent still lying in the womb of the earth! Like using ultrasound on a pregnant earth, we can view the future and wonder.

Yet in the midst of the relentless changes in Earth, planets, and stars, the color of a dragonfly’s wings, the song a bird sings, and the path my plane swings still matter—at least to other dragonflies, and to other birds, and to me.

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