The mountains that border Perry County seem timeless, but as this summer’s earthquake reminded us, the landscape — even here, among these placid hills — is still under construction.

In signs large and small, from subtle shifts in the bed of Shermans Creek to heaps of fallen rock by a road cut on Blue Mountain, the topography around us is changing.

In these parts, as opposed to some of the more violent places on earth, Nature’s pace is slow and stately. We don’t expect to wake up to find a smoking volcano on the horizon, or a newly minted island, still steaming, in the middle of the Juniata.

But just like the starfish, whose movements seem like random drifting to the naked eye, but whose purposeful swimming is revealed by time-lapse video, Perry County’s evolution is visible through the lens of geological time. The mountains are eroding. The valleys are silting up. Millimeter by millimeter, the tectonic plate far below us is shifting.

This was brought home to me last week by a rock I found next to our house. I was inspecting the shale that had been laid down by our friend Chad Shuman to give us a bit of a buffer from the summer weeds. I’d asked for local shale because it matches the roadbed to our house; I like the look of it; and it’s relatively cheap.

But I also had a hidden agenda: fossils.

I was something of a rock hound when I was a boy. My eyes were often glued to the ground. Minerals and crystals interested me, but what I really sought, in every gravel driveway and random heap of stones, was a glimpse of tiny ridges, or the chalky outline of a leaf, or even – and this was really wishful thinking – the serrated edge of an ancient shark’s tooth. Ambling along, plowing up likely suspects with the toe of a dusty sneaker, I pounced on anything that suggested a higher organization than the ordinary grains of ordinary rock.

Other obsessions have long since displaced my fossil-mania, but old habits die hard, and as I circled the air conditioning condenser that day, going about the grown-up business of peering through its fins to see if any weeds had gotten stuck inside, I couldn’t help glancing down every now and again, admiring the muted grays and greens of the shale, and looking for a telltale sign of prehistoric life.

And then, with a flash of recognition, I spotted the little beauty that’s currently on display next to my keyboard: a fluted gray seashell, outlined in a corona of orange and purple minerals that look suspiciously like a woman’s lips. In other words, a nearly complete fossil brachiopod.

I kept digging. Chad’s shale was full of fossils; it was fossiliferous in the extreme!

I was excited, and yes, it was certifiably dorky.

But there was something thrilling about finding an extinct marine bivalve next to the cold sheetmetal of the condenser.

I was interested in the source of this glorious shale, so I emailed the Shumans. Chad’s wife, Denise, informed me that the shale came from a pit behind Blue Mountain Processors, the mulch place on Route 74 below Ickesburg.

You may well ask, “How does a saltwater clam come to its final resting place near Ickesburg, approximately 600 feet above sea level?”

To answer that question, we’ll have to turn back the clock about 400 million years, to the Paleozoic Era, and more specifically, to the Silurian period. We’ll have to imagine a very different Perry County. I’m afraid it won’t look very familiar. The entire county is covered by a shallow inland sea. The collision with the European tectonic plate that will heave up the Appalachian mountains – perhaps to the height of the modern-day Himalayas – is still tens of millions of years in the future. The country is quite flat. Flat, and hot. At the moment, this corner of the proto-North American continent is fairly close to the Equator. It’ll be a long time before Perry County inches north to cooler climes.

The warm brine of this continental sea teems with underwater life, the only life that exists on earth. Dinosaurs are 200 million years in the future. Brachiopods cozy up in the mud along Route 74. Trilobites and other exotic creepy-crawlies scurry along 850.

How do we know all this? By the 3000-foot-thick layer cake of sedimentary rock that comprises the geology of Perry County today. I’d like to refer readers to an excellent publication, The Geology of the Hidden Valley Boy Scout Camp Area, Perry County, Pennsylvania, by John T. Miller and Richard B. Wells. If you do a quick Google search for it, you’ll find a free version to download.

This little book is a wonder of technical writing. My hat’s off to Messrs. Miller and Wells for taking a subject that’s literally dry as dust, and making it shine with wonder.

This column was published in the Perry Co Times on 27 October 2011

For more information, please contact Mr. Olshan at writing@matthewolshan.com