Two hikers tramp down the slope, pausing at a stream crossing. They’re both wearing NY Mets caps.

One  of the hikers calls over to us. “Hey, uh, there’s a bear back there on the trail.”

“A bear?” Matt replies. “How big?”

“Uh, we didn’t see. Just a bunch of people stopped on the trail talking about a bear. So we turned around.”

“Oh.”

Today I’m joining Matt and his friend Mike on a hike. Matt and I met three years ago in Pennsylvania, although I can’t pinpoint where I got to know him, exactly—we travelled together, from the east to South Dakota, Wyoming, Montana, Idaho, both swept along by the proverbial geology field camp experience.

Now Matt has a job not far from New York City. This weekend we’re exploring Minnewaska State Park Preserve.

“A bear?” Mike continues. “I don’t want a mess with a bear!”

“It’s just a bear,” Matt tells him.

“Exactly!” Mike exclaims. “It’s a bear!”

Matt looks to me. I shrug. “It’s probably gone by now,” I say.

Mike continues. “Didn’t you hear about the Rutgers student last year? Mauled and killed by a black bear!”

It was the first ever recorded death by black bear in New Jersey history. (NYTimes article here.)

“Why would a bear even be up here?” Matt wonders aloud.

I raise my eyebrows, pop a seedy huckleberry into my mouth, and start up the slope.

Matt documents the view from Milbrook Mountain, while I take a photo of him through the pitch pine, pretending I’m a bear.

We encounter no group of nosy people and no annoyed bear. Just chestnut oak and a dry trail.

At the Milbrook Mountain overlook, the ground drops away, and the Hudson Valley spreads out below us. Across the valley, the Hudson Highlands are veiled by a thick coat of haze. To the north, the Catskills look like a 19th century painting. Stunted oak and gnarled pitch pine line the cliff’s edge.

Near the precipice, Matt picks up a white, pebbly rock that looks a lot like concrete.

“It looks like concrete!” I exclaim, transferring my excitement from the pines to the rocks.

“White conglomerate,” Matt explains.

“Conglomerate? Isn’t that the indigenous word for concrete?”

Matt rolls his eyes.

I keep going. “Little known fact: concrete was actually mined here.”

I’m pretty sure Matt has stopped listening. “But then the Romans figured out how to make it locally, so you know how that goes…”

“Derek, I hope everyone realizes that the things you say about geology are usually made up.”

The Hudson Valley, with the Hudson Highlands in the background and the pebbly Shawangunk conglomerate in the foreground.

The Shawangunk Formation is a hard, silica-cemented conglomerate dotted with white quartz pebbles and bits of sandstone and shale. It’s a molasse deposit—the debris shed from a nearby mountain chain on the rise. In particular, the Shawangunk conglomerate was deposited by a braided river system that carried gravel and sand away from mountains that would now be, had erosion not done away with most of the evidence, 440 million years old.

As we pack up from our snack break at Milbrook Mountain, I bend down and point my camera at my feet.

“You know,” Matt says, “if someone compared your photos with mine, they’d think we went on a totally different hike…”

“They’re glacial striations!” I protest, my back to the scenic view. “And chattermarks!” Twenty thousand years ago, the scenery was more akin to that of Norway than New York. Beneath my feet are the footprints of the glaciers that dumped the foundations of Brooklyn’s rowhouses.

“OK, well, we’re going to keep hiking…”

The top of Shawangunk ridge is decorated with pitch pine and glacially polished conglomerate. (Apologies to my few dear readers who actually wanted to see a blurry closeup of glacial striations.)

The loop is eight miles long, and after a bit more hiking, we’re only halfway there. Just as I open my mouth to grumble about the heat and humidity, I feel a sudden, intense breeze–as if some divine power, so that it wouldn’t have to hear me complain, materialized an A/C unit three feet from my face.

“Ah!” Matt exclaims. “We’re coming up on the cave!”

Suddenly it dawns on me: Cave men didn’t live where they did because of the decor.

Inside a cave

Matt and I adventure into a crevice near Gertrude’s Nose Trail.

We spend a while relaxing at the cave entrance and exploring a nearby crevice. But on emerging back into the daylight, our shadows reminds us that we’d better pick up the pace, lest we end up stumbling back to the trailhead in the dark.

The rest of the hike to Gertrude’s Nose is nonstop scenic overlook. Cliffs of Shawangunk conglomerate jut out into the valley. Scree deposits line the base of the cliff, identical to the rock I’m standing on now. Red blazes mark the way, relegated from trees to boulders and ledges.

The Shawangunk Ridge–also referred to as the Shawangunk Mountains, or simply “the Gunks,” is the easternmost ridge of the Appalachians. In New Jersey, it’s called Kittatinny Mountain. In Pennsylvanian, it’s Blue Mountain. From space, it’s one continuous, sinuous line from Vermont to Maryland. If you count the Blue Ridge Mountains, the line goes all the way to Georgia.

Shawangunk Ridge once divided the “civilized” U.S. from the frontier. Today, it’s a cultural border, marking the eastern edge of Appalachia. To most, it’s just few seconds of radio static in the turnpike tunnel under Blue Mountain.

The trapps (ledges) of Shawangunk Ridge, wrapping around and into the background.

The rock that forms the ridge in Minnewaska State Park exists as a byproduct of the Taconic Orogeny,  but that wasn’t the conglomerate’s last run-in with mountain building. During the Paleozoic Era, plate tectonics used the eastern margin of North America for target practice:

The Potomac and Taconic. The Acadian. The Alleghanian. Island arcs and continents just kept coming, slamming into North America and leaving erosion to deal with the mess.

Collectively–along with a bit of puzzling “modern” uplift–these events formed the Appalachians.

Looking from Shawangunk Ridge into the Hudson Valley.

We skip across small crevices and enjoy the view. The silence of high places echoes with the click of camera shutters.

The light begins to yellow. “Time to head back to civilization,” Matt remarks.

I sigh. One hundred miles down the Hudson, the five boroughs bustle with people, and concrete rises from asphalt like trapps from glacial pavement.

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