It was early summer when I returned to the Potomac River bluff where I had found the rock with the carved cross. I removed the piece of rotting tree limb I had placed over it on my last visit and brushed away the fallen leaves. As the image came to view I thought how it always looked smaller and more crude than I had remembered, but just as enigmatic, with its main shaft topped by a diamond-shaped head and a line like a carpenter’s angle draped over one of the crosses’ arms.

I still had no idea what the image signified, or anything else about it, even after many visits. I’ve found plenty of fascinating clues, but none of the bits of glass, pottery, stone, and some oddball things as well, added up to anything. Each was a little story completely in and of itself. It was like astronomy before Newton.

This time, though, I was a little more optimistic. For I had come armed with an idea and some new information.

North to where? First, my idea. I took out my cell phone, flicked on the compass app, oriented the arrow north, and laid it alongside the cross. Just what I suspected: The digital age and the age of stone crosses lay in almost perfect alignment.

It was a “eureka!” moment. But while Archimedes’s flash of insight led to many scientific and technological discoveries, mine went nowhere.

What did it mean that the rock image pointed north? Why would a north-pointing rock be of any use to anyone? It’s not like people might forget which way is north, and needed a reminder. Was it a navigational aide for Santa Claus?

So as far as I could determine, my clue didn’t point to anything—except north.

Crinoid connection? Next, my new information. On my previous visit I had found what looked like a four-sided concrete post. Only the surface didn’t feel like concrete. It was smoother and more cushy. I had slipped a little piece in my pocket to check it out at home.

When I later looked at my sample under a lens, I saw that the ‘”concrete” was actually a mass graveyard of fossil marine fragments, a lot of them the familiar mini-donut segments of crinoid stems. It was limestone, probably formed sometime in the Ordovician period, around 450 million years ago. The closest limestone deposits occur about 30 miles away in the Hagerstown Valley.

Why would anyone go to the trouble of bringing carefully squared limestone posts to this place? Are they markers? Are they related somehow to the north-pointing “compass” rock?

I had already searched the web for old property markers. None looked anything like my stone. I did another thorough survey of site, hoping to find more limestone posts whose position would relate to each other in some way. I did find a couple more, but their placement appeared to be random.

Northward bound. Kneeling by the rock, I stared again at the cross, waiting for it to send me some signal. Maybe it was telling me to go north to find the answer. (Or maybe I had read too many Dan Brown thrillers.) At any rate, I set off, pushing through bushes and scrambling over rocks and logs. But aside from some broken bottles and rusty beer cans, I didn’t find anything, at least nothing that I could decipher.

See sidebar: Clues that go nowhere and beyond

This was getting frustrating. Could the rock be signaling some astronomical message? A lot of famous stone relics were created to mark astronomical events. Could my stone be a kind of mini-Stonehenge? I looked up to the heavens, but everything seemed in order—no eclipses, solstices, or meteor showers, just a Red-bellied Woodpecker hammering away at a dead snag at the top of an oak tree.

Distant rifle shot. I resumed my search along the bluff that overlooked the river. I found more glass shards and a few intact bottles, some old, some recent. Also rusted fragments of a car and a little rifle shell casing.

I carefully brushed away the dirt on the base of the casing and just barely made out “WRACO 25-20,” aka Winchester .25-20. You don’t see many of these any more. The cartridge was first introduced in1893 for the famed Winchester 1894 lever action rifle of Buffalo Bill and John Wayne fame. It hung around for years as a favorite of farmers, trappers, and pot hunters, since it’s relatively quiet and does minimal damage to meat and hides.

I  imagined what might have happened here many years ago. “John, John!” cried the farm wife. “The grey goose is gone, and the fox is on the town!”  Out ran John, just in time to see the fox—and the flapping goose—disappear over the hillside. John took a shot just to please his wife, and the crack of the rifle came back as an empty echo. The ejected casing landed where I found it.

Clues but no conclusion. Then there was the matter of that shallow pit near my stone. I slid down into the bed of leaves and broken branches, and started to feel around with my hands, hoping that copperheads by now had found cooler and moister refuges down by the river. I felt something metallic, which I pulled. It was a rusty metal strap, anchored below ground. To what? Without a shovel, I had no way of knowing.

When I later viewed the pit from a different angle I noticed what seemed to be a ring of rocks around its perimeter. Maybe it meant nothing—what else do you do with stones you find when you did a hole? Or maybe it told a story.

Before leaving I took a final look at the rock inscription before covering it over with leaves and the chunk of rotted tree limb. Clues were piling up, but so far they added up to absolutely nothing. Maybe things would start to come together on my next visit.

Or maybe I’ll never solve the mystery of the “compass rock.”

At the same time, my many hours on this bluff have taught me a great deal, things maybe even more important than the meaning of that particular rock or any of the other shreds of evidence I have found. What I have learned is this:

Here was a patch of forest overlooking the Potomac, lovely in its own right, but otherwise seemingly unremarkable. Yet, as I discovered through the bits of glass and flakes of stone, the circles of rocks and odd bits and pieces of human detritus, that spot has a conscious dimension that stretches back—who knows?—decades, centuries, maybe much longer. Even on a silent winter’s day, when nothing moves except the river, there are voices here.