Things I Like About Geology

In case you hadn’t noticed, I like rocks. Today, I’d like to share three of my favorite aspects of geology.

•• No matter where you are most of the geological story is missing. Consider Seattle for example. It’s a city surrounded by two mountain ranges and yet what do we see? Most of the rocks are less than 50 million years old, our volcanoes are less than a million years old, and glaciers formed our infamous Seven Hills just 16,000 years ago or so, which adds up to barely the tiniest record of planetary history. Even if you go to that great big chasm in Arizona, the oldest rocks in the Grand Canyon only push the clock back to 1.8 billion years, and tens of millions of years of more recent time, are not represented by any rocks.

I suspect that this smorgasbord of missing time gaps may trouble some, particularly the FOMO crowd, who worry that they are missing out on something amazing. They are, but as we will see in the next section, that’s okay because that lack of something also creates beauty.

•• Geology is fundamentally a battle between uplift and erosion. Take a gander at our volcanoes. You may know that geologists consider them to be active and they regularly erupt and spew debris like the rambunctious youngsters they are, but look again at Rainier, which seems a mighty edifice. Around 5,600 years ago, the top 1,000 feet blew off its top, and Mt. Saint Helens did the same thing, losing 1,300 feet of its summit in 1980. And, I haven’t even addressed the glacial scouring of the volcanoes that continues to carve away the slopes. Or consider our other non-volcanic mountains. In the North Cascades, huge swaths of the rock started life in the ocean, and even beneath it. Over time, plate tectonic movement pushed those rocks up thousands and thousands of feet but water and ice and wind have been unrelenting in their on-going work, taking that rock, reducing it to bits, and transporting it whence it came, back to the Pacific Ocean.

In fact, one geologist I know has argued that without erosion, the mountains would be sort of boring, basically a big plateau. Of course, such a plateau wouldn’t necessarily be featureless but it would lack the dramatic erosion-created topography that makes mountains such as the Cascades so stunning and beautiful.

If you are looking for someone, or something, to blame, or thank, for this situation, we have a culprit. Gravity. As that little known geologist Frank Sinatra crooned: “In time the Rockies may crumble, Gibraltar may tumble, They're only made of clay.” Well, technically they are made of stouter stuff but he got the idea right: What goes up must come down, no matter how formidable.

•• Geology is the science of deep time but there are also specific and discrete events preserved in the rock record. John Playfair wrote in the 18th century that “the mind seemed to grow giddy by looking so far into the abyss of time.” As I have written before, that giddiness of time is central to understanding geology and the power it has on Earth. Not all geology though is about deep time. Consider a varve, it is the thin layer of sediment deposited over the course of a single year in a lake. Of the 4.54 billion years of our splendid planet’s existence, a varve records just one, a lone year in the life of a lake. How could you not think that that’s amazing?

But wait there’s more, or actually, less. We also have single, discrete actions fossilized in rock. Known as trace fossils, they include an insect chewing a leaf, a clam’s burrows, raindrops splattering mud, a mammal biting a dinosaur, and a T. rex defecation. (Paleontologists have also reported on puddle-like pits in rocks hypothesized to have been formed by a rather larger beast tinkling.)

My favorite trace fossil are tracks, in particular from the legendary Portland Formation of Connecticut, the source for many of the brownstone buildings of the East Coast. Those trackways show dinosaurs walking on all fours, dragging their tails, resting a tush and breast on the ground, traveling in family groups, and fidgeting, or at least there are tracks where it looks like an animal stomped or patted his/her feet. Of the trillions and trillions of lives lived on Earth, trace fossils show that each was an individual, going through their daily existence eating, traveling, relieving themselves. And, of course, each more substantive, physical fossil represents both life and death.

A day in the life of some dinosaurs 200 million years ago.

Filling that deep, deep abyss of geological time are the uncountable moments of the animate and inanimate stories of the planet. For the most part, we only see the broad brush strokes of what happened before but occasionally the fine, and finest of, lines remain, and we are privileged to intersect geological time with our human time scale.