Stalking the wild amphibolite

Hikers clamber over remnants of oceanic crust created half a billion years ago.

The park ranger set the map on the countertop and traced his finger along a dotted line, first down the edge of Bear Island. and then upstream along the Potomac River’s Mather’s Gorge. Just past a spot marked TM-3 his finger stopped.

“Here it is,” he said quietly, almost to himself. “Amphibolite isn’t something you see much around here.”

I didn’t know much about amphibolite except that it was a dark rock with a violent and mysterious past. Even its name is beguiling. “Amphibole,” one of its  constituent minerals, means “ambiguous” in the ancient Greek.

Getting to know a new rock is always exciting—at least to me. It was getting late, but the trail looked short. If I hurried I could reach the spot well before dark.

Race to the rocks. Turning off the C&O Canal towpath I followed the blue marks on tree trunks that traced the trail through the stunted forest. Past a stream I came to a wall of rock. Up I scrambled, finding footholds for my boots and  feeling my leg muscles stretch as I stretched my arm to grab a handhold.

Every so often I looked around at the jumble of rocks, some grey, others black, many covered with blotches of light green lichen and tufts of moss, or even small trees growing out of cracks. Many of the rocks were cleaved into sharp angles, as if by a master stonecutter. I walked on bedrock smoothed into curves and hollows by the river’s abrasive floodwaters.

The rockscape was created over hundreds of millions of years by collisions of sections of the earth’s crust as they migrated over the earth’s mantle. Each collision threw up mighty mountain ranges and compressed and deformed sediments and debris and the very magma that welled up from deep under the earth’s surface. The Potomac region sits in the epicenter of these continental collisions.

I crossed a little beach and climbed another cliffside, then dropped down again, taking care with each footstep. Up and down, again and again—this was starting to be more work than pleasure. It was also getting late. I kept glancing at the sun as it sank over the hills across the river.

Maybe this wasn’t such a good idea? The rock I had wanted to meet as a new friend was now luring me along a path of slippery ledges, sharp crevasses, and plunging holes, each with the potential to twist my ankle, or worse. I checked my cell phone; the screen said, “No Signal.” I hadn’t left a note to say where I was going. I didn’t have a flashlight, or even my plastic orange whistle that was top rated by survival-mastery.com.

Then I came to a post—the same trail marker the ranger had showed me on his map.

Just as the amphibolite had intruded into the overlying sedimentary rocks, a tree drives apart the amphibolite.

Ancient fortress. A few steps further and I found myself in a realm of rock slabs like the remains of an ancient fortress. I examined a rock face and its coarse-grained pepper-and-salt pattern, heavy on the “pepper.” The dark mineral is hornblende, the common name for group of minerals found in many types of igneous and metamorphic rocks called amphiboles. The “salt” was  feldspar.

I ran my hand over the rock and felt its pebbly texture. These were amphibole crystals that had been exposed by weathering. The rock surface looked like the skin of the marine iguanas I once saw on the Galapagos Islands.

Now this was starting to get fun again. No matter that amphibolite is actually a common rock that is used for very mundane purposes. Polished to a shiny black, it’s a favorite for building facades and kitchen counter tops. Its toughness makes it a good aggregate for road construction and ballast for laying train track. The local Indians shaped amphibolite into tools for grinding corn and other foodstuffs.

Heat and pressure.The amphibilite was created here some 540 million years ago. This would put it in the period between two great mountain building events, the first when continents collided 1.1 billion years ago to form a super continent called Rodinia, and the second when an arc of volcanic islands slammed into North America’s east coast around 460 million years ago. In between, vast amounts of sediments swept into the ocean and cascaded down the slope on the edge of the continental shelf. These submarine landslides created sediment layers sometimes miles thick, producing heat and extreme pressure that forged the mud sand sand into shale and sandstone.

Framed by lichen, the weathered surface displays pebble-like crystals of amphibole.

Next, tabular masses of oceanic crust, called gabbro, punched up into these sedimentary rocks, where the same heat and pressure transformed them into amphibolite. I was standing on such a mass, one of a series of parallel deposits shaped like fingers that began on the opposite shore and passed underneath the river.

OK, time to go. Hurry, but take care, I kept telling myself. I continued on, up the rocks and down. I found the cutoff trail leading back to the C&O Canal towpath just as the moon appeared as a thin crescent over the hills. Back down by the river the usual owl was making its usual comments.

 

Meet the Potomac’s own philosopher

If the Potomac River has its own trickster (our friend Patowmack), why shouldn’t it have a philosopher as well?

Despite his life of despair (note the tear), Heraclitus teased posterity with a double-edged aphorism about stepping into rivers.

My philosopher of choice would be Heraclitus. As his name suggests, he was an ancient Greek, and he had some important things to say about rivers.

Member of a distinguished family, Heraclitus lived 2,500 years ago in the city of Ephesus, which was located on the eastern coast of the Aegean Sea in present-day Turkey. Through much of its history, this fabled city was a major commercial and religious center. Vestiges of its past glory survive today in the gleaming ruins of its temple, its vast amphitheater, and its great library. The city also figured in early Christian history as the probable origin of the New Testament’s Gospel of John.

Despite his illustrious homeland and family pedigree, Heraclitus led a lonely and ascetic life. He despaired of just about everything, and according to some accounts, at his life’s end he smeared himself with cow dung to cure himself from an unknown illness. The remedy proved ineffective, and his body was cast out in the street where it was eaten by dogs. Heraclitus was known as the “Weeping Philosopher.”

Restless rivers. Even if you have never heard of Heraclitus, you probably know his famous aphorism:

“You cannot step twice into the same stream.”

So true. Every time I go down to the Potomac I find a river that’s constantly reinventing itself, from year to year, from instant to instant. Its water flows clear one day, discolored the next. Mayflies are hatching one hour, then nothing but dragonflies an hour later. The water warms, then cools; its volume ebbs and flows; levels of oxygen and pH and other chemical indicators rise and fall in an ceaseless continuum.

A wall-to-wall carpet of stargrass one year nearly disappeared the next.

One year I’m dazzled by beds of stargrass that turn the river yellow from shore to shore; the following summer I find only scattered patches. An island recedes; a gravel bar forms upstream. I catch smallmouth bass along a stretch of shoreline one year; the next year only largemouth bass rise to my fly.

The restless river redraws its own geography. Mountain rivulets cut into mountain slopes and change the spot that marks the river’s sources. Downstream sediments build up and form oxbows that loop across the landscape. The sediments that reach its mouth create new land and extend the river further into the lake or sea.

All this is true, even obvious. But it hardly seems like the stuff of philosophy. Am I missing something?

Our mind’s river. It turns out that the idea of constant change was only part of what Heraclitus’ thinking about rivers. Here’s something else he said:

“On those stepping into rivers staying the same other and other waters flow.”

What to make of this? First off, Heraclitus could have used a good editor. (Actually, the blame for the clumsy writing likely goes to a compiler named Diogenes Laërtius, who wrote some 700 years after Heraclitus lived.)

I read the sentence over and over until my brain went into neutral. So I checked online to see what the experts had to say.

Now I think I get it, and it does seem to be legitimate piece of philosophical wisdom. Part of the idea is that rivers (and all else) must change, because otherwise they wouldn’t be rivers. Change is the very essence of a river.

But at the same time, rivers must remain the same—at least in our minds—to enable us to continue to speak of them as rivers. When we imagine a river, we conjure up the same image that we’ve had in the past and will continue to have in the future, despite the fact that the actual river itself is always different. Just by using the word “river,” we are implying that this object has essential qualities that we recognize as immutable. It’s kind of like a taxonomist’s type specimen, which anchors the defining features of a given species.

Heraclitus’ river. I’d like to think that Heraclitus had some kind of personal experience with an actual river. Not that this experience would be first-hand. I can’t imagine him taking delight in feeling the river mud squish between his toes or turning over rocks to see what lived there. He was a Weeping Philosopher, not a river rat.

Writhing across the valley, the Küçük Menderes shows how change defines a river.

If an actual river was the subject of Heraclitus’s philosophizing, it would have been the Küçük Menderes (also called Cayster or Kaystros), which flowed past Ephesus.

About the size of one of the larger tributaries to the Potomac, the Küçük Menderes today snakes through a mosaic of agricultural fields as it probably did even before  Ephesus’s founding.

Heraclitus would have found the Küçük Menderes a fine example of change. The river’s very name means “meander,” and so it has over the millennia, its channel looping first one way, then another, constantly on the move.

It’s also a silty river, and its currents continually transport these sediments downstream to its mouth on the Aegean Sea. The sediments create more land on the coast and extend the shoreline—along with the river’s mouth—further out into the sea.

Modern-day pilgrims to Ephesus’s Temple of Artemis come with cameras and tour guides.

As the shoreline marched westward, it left Ephesus behind. By 1000 BC the city’s harbor had turned to marshland, and Ephesus had to be moved closer to the sea and provided with a new harbor. Around 300 BC the port silted up again, and the city was moved once more. In the 5th century AD the harbor was abandoned. Today, the ruins of Ephesus lie landlocked about 4 miles from the sea.

A canal linking Ephesus to the sea bypasses the river that has silted up ancient harbors and left the city landlocked.

But this was not the end of it. The Turkish government now has a project underway to connect Ephesus to the sea, not by moving the ancient ruins, of course, but by constructing a canal to the ancient site. And in place of boats laden with grain and amphorae of wine and olive oil, the canal will now carry yachts loaded with tourists.

No doubt Heraclitus would have wept over his city’s transformation into a tourist attraction. But that is the price of change.

A Potomac alien gets its green card

I went down to the C&O Canal along the Potomac River on New Year’s Eve to pay tribute to a group of immigrants that had achieved an important milestone in 2017.

I’m not taking about America’s Muslims, Mexicans, Syrian refugees, or Dreamers, all of them targets over the past year of Donald Trump’s nativist attacks. None have anything to celebrate except their resilience and determination.

It turns out that the immigrants I had come to honor were not people, but fish.

On a day like that I didn’t actually expect to seen any. An icy wind lashed my face as my feet crunched along the frozen path. Even worse, there was hardly any water in the canal. It looked like a ditch. The only signs of life were sparrows chasing wind-blown seeds on the frozen puddles. But I knew my fish were out there buried somewhere in the mud, waiting out the winter.

I marveled at their toughness. They can adapt to just about anything, much like immigrants everywhere.

Come spring, some of them will slip through the crack in the intake gates at Violette’s Lock. From there they will push upstream to the west, through the rolling hills of the Piedmont and toward the distant mountains. They will find new places to live, good things to eat, and unforeseeable ways of getting eaten.

Tough, adaptable, restless: They seemed the very embodiment of the American spirit.

Fake news fish. In case you haven’t guessed already, my fish is the snakehead, or more precisely, the Northern Snakehead, known in scientific circles as Channus argus. I’ve followed the American adventure of this East Asian native since its appearance in 2002 in a pond behind a shopping center in Crofton, Maryland. As with many immigrants, its arrival was met with panic and paranoia.

They became the target of insults and name-calling, which is not surprising for a fish labeled “snakehead.” Even a Mafia hit man would blush at such a name.

Local reporters picked up the story and pretty soon the snakehead was dragged all over the national news, and even onto late night comedy shows. Writers who knew little about nature and nothing about fish took a handful of facts and turned them into a monster. Snakeheads grew big, are vicious, they have teeth. They can walk on land, breathe air, and are super tough and hard to kill.

Posters went up along local waterways: Wanted Dead Only.

It was code red fish alert. Unless something was done, the snakehead invasion would turn into an unstoppable fishkrieg.  The newcomer would decimate native fish species, and then lumber overland to devour neighborhood cats and dogs. They were the equivalent of Donald Trump’s Mexican immigrants–criminals, drug dealers, and rapists. For environmentalists, the new fish was an existential threat to “the ecology.”

‘Rip out its gills.’ First responders sprung into action. In a circus-like scene of reporters, cameras, and tee shirt sellers, state fisheries biologists launched a chemical attack on the Crofton Pond snakeheads. The campaign was a success, they reported. No fish in the 4.4-acre pond was left alive. The total cost was $110,000. The Nation’s Capitol heaved a sigh of relief.

Then snakeheads started popping up in ponds and streams everywhere. Government biologists and bureaucrats established new regulations and laws and ordered fishermen to mete out vigilante justice to any snakeheads they caught: Bash in its skull, freeze it, rip out its gills.

Came to (and then quickly left) a
theater near you.

B-movie producers raced to meet the demand for bad science fiction. Frankenfish and Snakehead Terror were released in 2004. Swarm of the Snakehead appeared in 2006, and Snakehead Swamp in 2014.

Of course, hardly anyone had ever actually seen a snakehead. But dragons and sea serpents, and monsters of all kinds, have been part of the human imagination for thousands of years.  People didn’t need facts to believe that snakeheads are creatures of the devil, right up there with Muslim bombers and Mexican criminals.

But despite all of this, today the fish is established throughout the Chesapeake Bay region. On the Potomac River snakeheads bypassed the Great Falls barrier, apparently by taking a detour on the C&O Canal.

Arm-wrenching strikes. While most people were getting their snakehead news from the media, some instead headed down to their local launching ramp to meet the fish in person. They went where the snakehead lived, paddling through thick mats of weeds and churning the mud bottom shallows with their outboard motors. What they found was startling.

Some were bass fishermen, like me. We had heard that snakeheads would decimate populations of that iconic (though also non-native) all-American sport fish. But we seemed to be catching as many bass as ever.

And on top of that, fishing had suddenly gotten a lot more exciting. My fingers would tighten on my fishing rod as a surge of water appeared behind my bait. The fish would strike with arm-wrenching force and then go airborne in an explosion of water and weeds.

Call it whatever name you wish, but the snakehead has become a prized game fish. “Doing any good?” I’d ask another fisherman as we paddled past each other. “No snakeheads,” he’d reply. “Just some bass.”

Surprise message. At the same time biologists were taking to the water with electroshocking gear, nets, and computers. One was Virginia state fisheries biologist John Okenkirk. I met him for the first time in 2011 at a lecture for group of bass fishermen assembled on the second floor of a local fire station. This was still back when snakeheads were assumed to be ecological enemy number one. His message took the audience by surprise: For whatever reason, bass populations appeared to be increasing—not decreasing—since the snakehead appeared on the local scene.

Odenkirk: The apostle of the
northern snakehead.

Odenkirk couldn’t hide his admiration for the maligned newcomer. He told how the snakeheads can bury themselves in mud to survive droughts. He described how the male and the female work as a team to guard their young.

He flashed a photo of a snakehead on the screen, its muscular flanks patterned brown and coppery. “That is some pretty fish,” he said. The men in the room nodded.

Just another fish. The snakehead was winning admirers, but its acceptance still wasn’t official. Then something happened this past year that didn’t exactly amount to permanent resident status, but it came close.

It was the same John Odenkirk, but this time in an interview he gave for an article in the May 2017 issue of Virginia Wildlife, the official magazine of the Virginia Department of Game and Inland Fisheries. In one sentence he popped the hysteria bubble of the previous 15 years.

“They [snakeheads] seem to have reached an equilibrium with the other fish in the river and they occupy a niche that was largely unfilled,” he said.

Article author David Hart summed it up:  “Snakeheads, it turns out, are just another fish.”

Massive wooden gates at Violette’s Lock
proved no match for snakeheads.

A real American.  My walk along the canal ended at Violette’s Lock. I stood on the wall of great sandstone blocks that anchored the intake gates. These massive wooden doors block passage from the canal to the upstream river system. If you believe in border walls, you would be impressed.

But snakeheads, like Guatemalans reaching the US border, are tough to intimidate. For several years fish have been moving through the crack where the two gates swing together. They swim along some little islands and log piles, maybe pausing in a thick bed of stargrass. There they might rise up to take a little gulp of air (yes, snakeheads do breathe air).

If they looked across the river they would see the Trump National Golf Course. They might even see Trump himself bouncing along in a little golf cart like a remote controlled toy.

Of course Trump doesn’t know about snakeheads and the intake gate at Violette’s Lock. He doesn’t know about the river, or even much about America and what truly makes this country great.

The image of a snakehead out there in the river, swimming westward would mean nothing to him. It would be left for others to say, “There goes a real American.”