Drilling Down to Where the Body Starts

GLEN ROSE FORMATION | Lower Cretaceous, Aptian-Albian, 112 Ma | Alternating limestone and marl, rudist reef facies, thickness 300–500 ft

The road cut on Ranch Road 1431 west of Cedar Park exposes the Glen Rose Formation in cross-section, a wall of cream-and-gray rock that, if you are driving sixty-five in a pickup with the windows down and the radio scanning for something besides Jesus and drought reports, looks like nothing — like Texas being Texas, which is to say being rock and heat and road. But if you stop, if you pull onto the gravel shoulder where the semis have worn two pale ruts in the caliche and you walk to the cut face and put your hand on it, what you are touching is a reef. Not the skeleton of a reef, not the memory of a reef, but the reef itself, lithified: the calcium carbonate of rudist bivalves, which were fat, conelike clams that grew in thickets on the floor of a shallow tropical sea and built, over thirty million years of growing and dying and accreting, a platform of biogenic carbonate that is now the bedrock of the Texas Hill Country, that is now the thing the cedar fence posts are anchored into, that is now the road cut on Ranch Road 1431 where the semis haul gravel from one place that used to be a sea to another place that used to be a sea.

The rudists are everywhere in the Glen Rose if you know what you’re looking at: their conical shells bisected by the saw cuts of road construction, their cross-sections revealing growth rings like trees, their fossils embedded so densely in certain beds that the rock is more organism than mineral, more archive than substance. I ran my thumb along a rudist cross-section the diameter of a coffee mug. One hundred and twelve million years ago, this animal was filtering seawater in a lagoon. Now my thumb was in its ribcage.

I should say that I am not a geologist. I write about geology for Hill Country Monthly, which means I translate. I turn the Cretaceous into a feature, the Balcones Fault into a sidebar, the karst hydrology of the Edwards Aquifer into something a person might read in a dentist’s office and carry away as a fact they could repeat at dinner. I am good at this. I have been told I write about rock the way rock deserves to be written about, which is something a geologist said to me once at a conference in San Antonio, a man with a gray beard and a Brunton compass clipped to his belt who looked at me and said you write about rock the way it deserves, and which I have carried as a compliment longer than I should admit, because what I heard in it was not you write well but you see clearly, and those are different things, and only one of them is true.

The other thing I should say is that I have always been more comfortable describing the world than describing myself. The world holds still for description. A road cut does not flinch. A rudist bivalve, cross-sectioned and exposed, does not rearrange its history depending on who is looking. People do. I do. I have, over the years, developed a vocabulary for the nonhuman world that is precise and faithful, and a vocabulary for my own life that is approximate, evasive, and full of geological metaphors I deploy the way a hermit crab deploys a shell — not as decoration but as architecture, as the only structure available for an organism that cannot grow its own.

The technician asks you to hold still.

The Glen Rose is divided into upper and lower members. The lower member — what is exposed at this road cut — is predominantly limestone, dense and resistant, the reef facies. The upper member is softer: alternating beds of limestone and marl, the marl being a calcareous mudstone that weathers faster and recedes, leaving the limestone beds protruding like shelves on a bookcase with the books removed. This differential weathering creates the characteristic stair-step topography of the Hill Country, the terraces and ledges that real estate developers call “Hill Country charm” and geologists call “a function of lithological heterogeneity.” The same thing, described twice, meaning nothing alike.

I drove to the Balcones Fault Zone on a Tuesday in November. I had my notebook and my rock hammer and a printout of the stratigraphic column for the Balcones Escarpment, which I had laminated at the FedEx on Lamar, and which I kept on the passenger seat weighted down with a piece of Glen Rose limestone the size of a fist that I’d picked up on a field trip two years ago and never returned to the earth, which makes me a thief, technically, though the statute of limitations on Cretaceous reef fragments is unclear.

The real reason I drove to the fault zone is not the one I would have given you if you’d asked. I would have said the magazine piece. I would have said research. I would have held up the laminated column and pointed to the formations I planned to visit, named them with the confidence of someone who knows what she’s looking at, and you would have believed me, because I am convincing when I talk about rock, more convincing than when I talk about anything else, and I have built a life in which this passes for enough.

EDWARDS FORMATION | Upper Albian to Cenomanian, 97–100 Ma | Dense gray limestone, karst porosity 15–30%

Porosity is the percentage of a rock that is empty space. In the Edwards Formation — the thick, dense limestone that caps the Hill Country and forms the primary unit of the Edwards Aquifer — porosity ranges from fifteen to thirty percent, which means that up to a third of this apparently solid rock is void. Holes. Passages. Voids dissolved by slightly acidic groundwater over tens of millions of years, the carbonate dissolving molecule by molecule until what remains is a Swiss-cheese architecture of solid rock surrounding empty chambers, conduits, fractures, vugs. The water that comes out of your faucet in Austin, if you live on the aquifer, has been filtering through these voids for anywhere from ten to ten thousand years, depending on the flow path, depending on the rain, depending on how you define “the same water.”

I think about porosity more than a person should.

Three weeks before I drove to the fault zone, I lay on a narrow padded table in a medical office on West 38th Street while a DEXA machine scanned my left hip, my lumbar spine, and my distal radius. DEXA stands for dual-energy X-ray absorptiometry, which means the machine sends two X-ray beams of different energies through the body and measures how much each beam is attenuated by bone versus soft tissue. The attenuation differential allows the software to calculate bone mineral density: grams of calcium hydroxyapatite per square centimeter. The body, rendered as a density map. The body, translated into a number.

My number was -1.8.

I sat in the radiologist’s office while she explained what this meant. She had a model of a hip joint on her desk, the kind made of white plastic with a cutaway showing the trabecular bone inside — the spongy, latticed interior structure that gives bone its strength relative to its weight, the engineering of it, the architecture. I stared at the model while she talked. I thought: the inside of a bone looks like the inside of a karst limestone. The same lattice. The same voids. The same tension between structure and space.

The -1.8 is a T-score, which compares your bone density to the peak bone density of a healthy thirty-year-old woman. A T-score of 0 means you are average. A T-score of -1.0 or higher is normal. A T-score between -1.0 and -2.5 is osteopenia — bone thinning, the preliminary stage, the yellow zone on the chart the radiologist showed me, which was printed on a graph that looked, I noticed and immediately wished I hadn’t, like a stratigraphic column turned sideways: density plotted against age, my data point dropping below the green band into the yellow, falling through the normal the way a formation drops through a fault, one side staying where it was while the other side moves down.

I am forty-one. My bones are older than I am.

The Romans measured everything from the body. The digitus — finger-width, 18.5 millimeters — was the smallest unit of length. Sixteen digiti made a pes, a foot. The cubitum was elbow to fingertip. The uncia, from which we get both “inch” and “ounce,” was one-twelfth of a foot, because the Romans loved twelve the way we love ten, because twelve divides more generously: by two, three, four, and six, making it the natural base for a civilization that measured the world by halving and thirding and quartering the human body outward into space.

The technician who operated the DEXA machine positioned my arm. She measured my wrist with a flexible tape — twenty-seven digiti, though she didn’t say this — and typed the measurement into her computer. She measured the distance from my hip to the table’s edge. She asked my height and my weight and whether I had ever broken a bone. I said no. This was true and also, I thought, beside the point. The question is not whether the rock has fractured. The question is how much of it is empty space.

WALNUT FORMATION | Lower Cretaceous, Albian, ~105 Ma | Nodular limestone with oyster biostromes

The Balcones Fault Zone runs northeast to southwest through central Texas, roughly following Interstate 35 from Dallas to San Antonio, a line that also happens to divide the state into its western, ranching, increasingly arid half and its eastern, farming, Gulf-facing half — a cultural fault that overlays the geological one with an eerie precision that is probably coincidental and is certainly not. The Balcones Fault is not a single fracture but a system of en echelon faults — parallel fractures arranged in a stepping pattern like bricks in a wall — along which the Edwards Plateau was uplifted (or, more accurately, along which the Gulf Coastal Plain was dropped) a total of twelve hundred to sixteen hundred feet of vertical displacement. One side went up. The other went down. What had been a single continuous surface became a scarp, an escarpment, a line you can see from space where the rock and the light and the vegetation change, and if you stand on the high side and look east, the land falls away beneath you as though it has been cut.

I stood on the high side. I was at a pull-off on Route 281 north of Blanco where the fault scarp is visible as a change in the landscape’s fundamental geometry — the flat plateau behind me, the lower, rolling country ahead, and between them a drop that happened not gradually, not over eons of gentle subsidence, but in a series of ruptures, each one catastrophic in geological terms, each one shifting the rock a few feet or a few dozen feet in a single event that would have been an earthquake if anyone had been alive to feel it, which no one was, because the faulting began in the Miocene, fifteen million years ago, when the only witnesses were the ancestors of horses and the ancestors of camels and whatever else was grazing on a savanna that no longer exists in a climate that no longer obtains.

The displacement is twelve hundred feet. I wrote this in my notebook and then stared at the number. Twelve hundred feet is the height of the Empire State Building without the antenna. Twelve hundred feet is the depth to which you would have to drill, starting from the low side, before your bit would reach the layer that is sitting at the surface on the high side. The same rock, the same age, the same formation, separated by twelve hundred feet of vertical distance because one side moved and the other didn’t. An unconformity of position. A gap you can measure but not close.

You are in the waiting room. You are holding a magazine you have not opened. You are the only body here that is not behind a door.

I have not told my mother about the bone density scan. She lives in Montclair, New Jersey, in the house where I grew up, a house with a foundation made of Watchung basalt, which is a Triassic flood basalt, which means the rock her house sits on is two hundred million years old and was formed by a volcanic event associated with the breakup of Pangaea, and I know this because I am the kind of daughter who can tell you the age of the rock under your house but cannot tell you what is happening inside her own bones.

She would worry. She would look up osteopenia on WebMD and call me back with a list of calcium-rich foods. She would ask if I’m eating enough, and this question, from her, aimed at me, has never been just a question. The last time she asked me if I was eating enough I was seventeen and the answer was no and she did not ask the next question, which was why, and we have been standing on either side of that unasked question for twenty-four years, a displacement neither of us knows how to measure because neither of us has admitted it exists.

COMANCHE PEAK FORMATION | Lower Cretaceous, Albian, ~105–100 Ma | Massive limestone, abundant echinoids

The Comanche Peak is the quietest formation in the Balcones column. Massive — meaning without visible bedding planes — and so uniform in composition that it weathers into rounded, featureless slopes, the opposite of the stair-stepped Glen Rose. It is the formation you drive past without seeing. It is the rock that does not call attention to itself. It is limestone made of things that died so long ago and in such profusion that they have lost their individuality, their fossil forms dissolved into a homogeneous gray paste of calcium carbonate, the original organisms — echinoids, foraminifera, the tiny planktonic shells that rained down through Cretaceous seawater like snow — now indistinguishable from one another, now just rock, now just the thing you build a retaining wall out of.

I moved to Austin six years ago. I moved because my marriage ended, though I told people I moved for the geology, which was true enough to pass. I was thirty-five and suddenly in possession of a life I did not recognize, and Austin was a place I had visited for a conference and remembered as hot and strange and full of exposed rock, and I thought: I can live somewhere that shows its bones. I can live somewhere that does not pretend to be smooth.

What I did not think, or did not allow myself to think, was that I was also moving thirteen hundred miles from my mother, from the house on the Watchung basalt, from the specific latitude and longitude of a set of memories I had been carrying since I was seventeen, and that the distance was not incidental, and that geology was not the only reason a person might want to be surrounded by evidence of deep time, by proof that the present is thin, that the present is a surface, that everything that matters is either far below or long ago and in either case unreachable by the ordinary instruments of conversation.

I am half-Nigerian, half-Irish-American, and I have my father’s cheekbones and my mother’s tendency to make lateral moves when a direct approach would be more efficient. My father died when I was twenty-three. He was a civil engineer who understood foundations, who could look at a plot of land and tell you what was underneath it, what it would bear. He did not talk about this as a metaphor. He talked about it as soil mechanics. The angle of repose. The bearing capacity. The point at which the ground fails.

I think he would have understood the T-score, would have seen it the way I saw it: as a structural problem. A load-bearing problem. The bones as foundation, and the foundation thinning.

There is a thing that happens when you are a woman in a doctor’s office. They measure you. They measure your weight and your blood pressure and the circumference of your upper arm and the distance between landmarks on your skeleton, and each measurement is entered into a system that compares you to a standard, and the standard is always someone else — a composite, an average, a thirty-year-old woman at peak bone density who exists as a data set and has never existed as a person. The T-score is a distance from her. My T-score tells me how far I have fallen from a woman who is not real. The entire diagnostic framework is a measurement of absence — not what you have but what you have lost, not where you are but how far you’ve drifted from where you were supposed to be.

My mother would understand this, though she would not use these words. She has spent her life being measured by standards she did not set, in rooms where the instruments were calibrated to someone else’s body. She is a Black woman in New Jersey. She knows about measurement. She knows about the gap between the real and the expected. She would not need me to explain the T-score. She would need me to explain why I didn’t tell her.

The body I arrived in Austin with was not the body I have now. I do not mean this metaphorically. I mean my skeleton has measurably changed. The calcium has leached. The mineral density has dropped. The bones are the same bones — the same femur, the same vertebrae, the same distal radius the technician measured — but they are less of themselves, the way a limestone formation exposed to acidic groundwater is still limestone but is also, increasingly, void. Porosity increases. Structure remains. The shape of the thing persists long after the substance of the thing has diminished. This is what haunting is. Not the presence of something gone but the structure it left behind, intact, load-bearing, empty.

UNCONFORMITY | ~40 million years absent | No record

In a stratigraphic column, an unconformity is a gap — a place where the expected sequence of formations is interrupted by the absence of rock that should be there. The rock was deposited, existed, and was then removed, either by erosion or by uplift followed by erosion, and what remains is a contact between two formations that should not be in contact, separated by a silence of millions of years, the missing time represented by nothing, by a line on the column, by the notation ~40 million years absent.

The Balcones column has a major unconformity between the Cretaceous limestones and the older Paleozoic rocks beneath them. Forty million years of earth history, gone. Not hidden, not compressed, not preserved in some other location. Gone. Eroded to sediment, carried to the sea, deposited somewhere else or nowhere, the record destroyed so completely that we cannot reconstruct what happened during those forty million years except by analogy with other places where the record survived, which is to say we know what happened only by looking at places where it did not un-happen.

I was seventeen.

It was August. It was New Jersey. It was hot the way New Jersey is hot — humid, close, the air thick enough to feel on your skin like a second skin you cannot remove.

His name doesn’t matter. What matters is that I trusted him and that trust was a structural error, a miscalculation of the bearing capacity of another person. What matters is that afterward I stopped eating. Not as a decision. Not as a project. More like a withdrawal, the way groundwater withdraws from an aquifer during drought — not because it chose to leave but because the conditions that kept it in place changed. The conditions changed. I stopped eating. Three months. My mother asked if I was eating enough and I said yes and she chose to believe me because the alternative was a question neither of us had language for, a question that sat in the gap between us like an unconformity, forty million years of unrecorded time, a silence so complete it became the foundation, the thing everything else was built on top of.

I did not disappear. I wanted to. I wanted my body to become less — less visible, less present, less available to the world’s opinions about what it was and what could be done to it. I wanted to reduce my body to its mineral components, calcium and phosphorus and the trace elements that remain when everything soft has been removed. I wanted to be geological. I wanted to be rock.

I was not rock. I was a seventeen-year-old girl in New Jersey who stopped eating because a boy in a car did something to her body that she could not undo, and because the only response she could imagine was to make that body smaller, to erode it, to become her own unconformity — a gap in the record where something should have been.

The bones remember. Twenty-four years later, the DEXA machine found the evidence: a T-score of -1.8, the mineral density of a woman whose skeleton recorded the three months she did not eat, recorded it the way rock records the conditions of its formation, faithfully, without judgment, without deciding what matters and what doesn’t, the way the Glen Rose Formation does not decide which fossils to preserve and which to dissolve but simply responds to the chemistry of the groundwater and the pressure of the overburden and the patience of one hundred and twelve million years.

BASEMENT ROCK | Precambrian, >1 Ga | Metamorphic gneiss, no fossils

Dolores Ramirez has been caving in the Hill Country for thirty-one years. She is sixty-three, five-foot-two, and moves through a karst passage the way water moves through a karst passage, which is to say she finds the path of least resistance without appearing to look for it, her body reading the rock the way a sentence reads its own grammar, each joint and twist anticipated by some spatial intelligence I do not possess and cannot learn from a manual.

We descended into a sinkhole four miles west of the fault scarp, on private land whose owner Dolores identified only as “a rancher who understands that what’s under his property is more interesting than what’s on top of it.” The entrance was a vertical slot in the Edwards limestone, partially concealed by a juniper growing at an angle that suggested the tree had opinions about gravity. Dolores rigged a handline. I followed her down.

The temperature dropped ten degrees in the first twenty feet. Then another five. Then the light changed — not dimmed, exactly, but shifted from the flat, white, omnidirectional glare of a Texas afternoon to something directional and gray, the light falling from the entrance above like a column, a visible shaft that illuminated the dust motes we dislodged from the rock and left everything outside its beam in a darkness that was not empty but thick, textured, the darkness of a space that has been dark for a very long time and has developed its own qualities in the absence of photons, the way silence in an old room is different from silence in a new one.

The walls were wet. Not dripping — seeping, the moisture distributed through the rock in a film so thin it was more a quality of the surface than a presence on it, as though the limestone were sweating, as though the rock remembered being underwater and was expressing that memory through its pores. I pressed my palm flat against the wall. The stone was cool and faintly gritty, the texture of calcium carbonate that has been dissolving for millennia at a rate too slow to see but too persistent to resist: one millimeter every hundred years, roughly, depending on the acidity of the water, depending on the carbon dioxide content, depending on the temperature, which was fifty-eight degrees Fahrenheit in this passage and had been approximately fifty-eight degrees Fahrenheit since before there were units called Fahrenheit.

“Watch the ceiling,” Dolores said. I looked up. Embedded in the limestone above my head, a crinoid stem — a columnals, the segmented stalk of a sea lily that had anchored itself to the Cretaceous seafloor a hundred million years ago and was now a fossil in a cave ceiling in Texas, its circular segments stacked like vertebrae, like a spine, like the thing the DEXA machine measured in my lower back three weeks ago when the technician asked me to hold still and the X-rays passed through my body and measured the density of the bone and found it wanting.

Further on, the passage opened briefly into a small chamber, maybe ten feet across and just tall enough to stand in. Dolores stopped and turned off her headlamp. “Wait,” she said, and I turned off mine. The dark was total. Not dark-with-your-eyes-closed, which always contains the residual light of the eyelid’s capillaries, but dark-with-nothing — the absolute absence of photons, the kind of dark that existed everywhere before there were eyes, the original condition of the interior of the earth, which has been dark for four and a half billion years and will be dark for four and a half billion more and does not care, does not know, does not register the two women standing inside it with their lights off and their pupils dilating uselessly.

The sound changed too. Above ground, you are never in silence — there is always wind, traffic, the electrical hum of infrastructure, the distant barking of someone’s dog. Here there was only the drip of water somewhere ahead and the sound of my own breathing, which was louder than I wanted it to be, each exhale a small weather system in the closed air of the chamber. I could hear my heartbeat in my ears. I could hear Dolores shift her weight on the gravel floor. I could hear the cave, if a cave can be said to make a sound, a low, barely-there resonance that might have been water moving through passages deeper than this one or might have been the rock itself conducting vibrations from the surface — the rumble of a truck on a ranch road, attenuated by four hundred feet of limestone into something felt rather than heard, a pulse in the stone.

“Time moves differently down here,” Dolores said, and she was right, though not in the mystical sense — she meant that without light cues, without weather, without the sun marking its arc, the body’s sense of duration detaches from the clock. We had been underground for what I estimated was forty minutes. It had been an hour and ten.

The passage narrowed. Dolores went first, turning sideways, her headlamp sweeping the walls and casting shadows that moved like something alive. I followed. The ceiling lowered. The walls pressed in. I had to crouch, then duck-walk, then flatten myself against the rock and slide forward on my stomach, my chest against the limestone, my hip bones — my thinning hip bones, my osteopenic hip bones, the bones that registered -1.8 on the DEXA — pressing into the floor of a cave formed in rock that was itself made of bones, the calcium carbonate of ancient shells, the compressed remains of organisms that lived and died and sank and lithified, and I was lying on top of them, my bones against their bones, my calcium against their calcium, separated by a hundred million years and a T-score and the thin, warm fact of my own aliveness.

I was underground in Texas, in the dark, in the compressed remains of a sea that dried up sixty-five million years before I was born, and I was trying to do something with the shame I have carried since I was seventeen. Not dispose of it. I don’t think shame disposes. I think I was trying to put it somewhere — to press it into the rock the way the rock had pressed itself into the rock beneath it, layer into layer, weight into weight, until the original material is no longer what it was but is still there, altered, bearing the load of everything deposited after it.

It didn’t work. The shame sat there, geological. It was part of the column. It had always been part of the column.

“You okay?” Dolores called back. Her headlamp was a distant point ahead of me, a star in a formation that contained no stars.

“Yeah,” I said. The cave swallowed the word. The limestone absorbed it the way it absorbs water — slowly, through pores, at a rate that does not care whether you are watching.

I could not go further. The passage narrowed beyond what my body could negotiate, which was the body’s way of saying this is as far as you go, which was also the essay’s way of saying it, the form reaching its limit, the drill bit hitting a layer it cannot penetrate — not because the layer is harder than the others but because the bit was designed for a certain depth and this is it.

You are in the doctor’s office. The paper on the examination table crinkles when you shift your weight. The fluorescent light is the light of no particular time, which is the point — the medical office exists outside of time, outside of weather, outside of the specific November afternoon that is happening on the other side of the window, the one with the live oak dropping leaves on a Honda Civic in the parking lot.

You are seventeen. You are sitting on the edge of your bed in New Jersey, and the window is open because it is August and the air conditioning is broken, and through the window you can hear the neighbor’s sprinkler and somewhere, further away, an ice cream truck playing a song you will never be able to hear again without flinching, not because of the song but because of the day, because of what happened earlier that day, because the song was playing when you came home and walked through the front door and went to the bathroom and turned on the shower and stood under the water and felt your body as a foreign object, a thing that had been somewhere you did not send it, a thing that had been used in a way you did not authorize, and the water ran over you and you stood there and the song played outside and you stood there and the water ran and you stood there.

You are twenty-three and your father has just died and you are standing in the kitchen of the house in Montclair and your mother is sitting at the table and neither of you is talking. The house is on Watchung basalt. The basalt is two hundred million years old. Your father knew this. He built things on top of old rock and he trusted the rock to hold and it held and he did not hold and you are standing in the kitchen and the countertop is granite and granite is an igneous rock and your father could have told you its mineral composition without looking and he is not here to tell you and the rock is still here and he is not.

You are forty-one. You are lying on a table while a machine reads your bones. The technician has positioned your left arm in a cradle and you are looking at the ceiling tiles and counting the perforations in the ceiling tiles because this is a thing you can do, a thing that does not require you to think about the graph, the T-score, the yellow zone, the fact that your skeleton is carrying the minutes of a meeting that happened twenty-four years ago. The technician has brown hair pulled back with a clip and she calls you “hon” and she does not know anything about you except your date of birth and the circumference of your wrist and the reason for the referral, which is “routine screening,” which is a lie, because nothing about this is routine, because you requested this scan yourself after reading a journal article about the long-term skeletal effects of adolescent malnutrition, which you read because you read everything about the body now, because the body described in a journal is a body you can close.

You are neither of these. You are the unconformity between them — the missing time, the gap in the record, the twenty-four years that passed between the shower and the scan, years during which you finished high school and went to college and graduated and got a job and got married and moved to New Jersey and then to Austin and wrote about rock for a magazine and learned the names of formations and the ages of limestone and the six types of porosity and the mechanics of karst dissolution, all of it real, all of it lived, and none of it the thing that happened, which sits beneath all of it like basement rock, like Precambrian gneiss, the oldest thing in the column, metamorphosed beyond recognition but still there, still bearing the weight of everything above it.

You put your glasses on. You take your glasses off. The room is the same room. The body is the same body. You are still here, which is not a triumph and not a failure but a fact, the kind of fact a geologist would note in a field report without commentary, the way you would note the thickness of a formation or the angle of a fault plane: observed, recorded, present.

SURFACE | Holocene, present | [no data]

I climbed back out. Dolores went first, her boots finding holds in the rock I could not see until her headlamp illuminated them from above, and then I followed, hand over hand, the handline rough against my palms, my body pulling itself upward through formations it had descended through — Edwards, Glen Rose, the contact zones, the small solution cavities where bats had left guano deposits that smelled of ammonia and time — and then the light hit me, the flat white Texas light, and the heat, and the wind carrying the smell of cedar and dust, and I was standing at the lip of the sinkhole looking out at the fault scarp, the long, visible line where one side of the earth sits twelve hundred feet lower than the other.

The juniper was still growing at its angle. The rancher’s fence line ran along the escarpment, cedar posts in Glen Rose limestone, barbed wire catching the late-afternoon light. A red-tailed hawk was circling something in the lower country, east of the fault, riding a thermal that existed because the escarpment creates its own weather, the warm air rising along the exposed rock face and generating updrafts that the hawks have been using for as long as there have been hawks and escarpments, which is not as long as there has been limestone but is longer than there have been fences or ranch roads or science journalists standing at the edges of sinkholes trying to figure out what kind of essay they are writing.

I took out my phone. I called my mother. It was 4:47 p.m. in Texas, 5:47 in New Jersey, a time when she might be making dinner or watching the news or sitting on the back porch looking at the Watchung Ridge, which is a Triassic basalt formation, which I have told her about many times, which she has listened to without interrupting, which she has never asked me to stop talking about because she knows, I think, that when I talk about rock I am talking about something else, and she is willing to wait for me to say what it is, and she has been waiting for twenty-four years, and I have not said it.

The call went to voicemail. Her voice, recorded, said her name and asked me to leave a message. I listened to the beep. I held the phone to my ear. The hawk was still circling. The wind was still moving through the cedar. The fault scarp extended northeast and southwest as far as I could see, the line where the earth broke and one side dropped and the surface that had been continuous was now two surfaces, separated by twelve hundred feet of displacement that you cannot undo, that you can only measure, that you can only stand on one side of and look across.

I did not leave a message. I held the phone against my ear and listened to the silence after the beep, the digital silence that is not silence at all but a recording of silence, a representation, and then I hung up and put the phone in my pocket.

The geological column was complete except for this layer — the surface, the Holocene, the present — which I had left blank in my field notes, which I was supposed to fill in with observations about the current landscape, the soil type, the vegetation community, the land use, the evidence of human habitation, all the things that sit on top of the rock and pretend to be the point. I looked at the blank space on the laminated column. I could not fill it in. The drill bit was still turning. The surface is the layer that is still forming, and I was inside it, and the instrument and the subject were the same.

The hawk descended. The light moved. I sat on the caliche shoulder and watched the fault scarp do nothing, which is what a fault scarp does after the displacement is finished, which is what it has been doing for fifteen million years, which is longer than I needed to sit there but not as long as I wanted.