Nile Builder: The Architect from the East

Chapter 34: Chapter 10: Scouting the Hinterlands --- Diagnosing the New Capital’s Foundation Flaws in Advance

After Mehptah and his five companions joined the column, the caravan pressed east for another five days. The gravel plain gradually receded behind them, and ahead the terrain abruptly opened -- here the Nile bent eastward in a great loop nearly ten li across; the lands flanking the river were no longer red sandstone and black gravel, but an endless desert plain. The skyline stretched into a single nearly horizontal long arc, extending boundlessly toward a distance where no building outlines had yet been decided.

Over these five days, the caravan advanced from the semi-desert zone of the gravel plains in a steady east-by-northeast direction. On the first day, scattered tamarisk and camel-thorn could still be seen beside the road -- the roots of those low shrubs drove extraordinarily deep, their leaves abraded gray by windblown sand, the leaf margins curling into fine tubes to conserve what internal moisture remained, proof at least that within a dozen or so cubits underground there was still enough humidity for plants to tap. By noon of the third day, tamarisk had vanished entirely from view; before sunset on the fourth day, even the camel-thorn no longer appeared -- the last withered camel-thorn on the ground, its root-stem long since hollowed out by wind-driven sand, was all that remained: a thin, brittle husk thrust diagonally into the sandy soil. As Kamon passed, he nudged it lightly with his foot, and the entire desiccated husk shattered into a heap of powder.

The soil underfoot underwent a visible gradation over the five days. On the first day it was a gray-brown coarse-sand and gravel mixed layer, the stone fragments still angular, with the familiar grating sensation underfoot -- alluvial gravel carried from an old Nile riverbed. On the second day, the coarse-sand proportion began to drop, fine sand welling up from between the stones. By the third day, the tactile sensation underfoot had become a soft, silty-sand texture; the ruts left by cartwheels no longer formed hard-edged cracks but soft impressions that slowly rebounded after collapsing -- a sign that the moisture content of the soil layer below was dropping fast. Starting the fourth day, the entire ground surface turned into pale yellow-white fine sandy dust; it no longer crunched with gravel under the soles, but with each step the ankle sank a finger’s depth into floating dust, and pulling the foot free raised a small cloud of powder so dry it was nearly weightless, powder that hung suspended in the air a long while before slowly settling back to the ground.

The moisture in the air dropped day by day. On the first morning, the outer wall of the waterskins slung from the cart shafts still formed a thin layer of condensation beads -- the last wisp of humidity brought from the river surface by the day-night temperature swing, the beads sliding down the skin to pool in a small sip of cool water at the bottom. On the second day, the beads grew sparse, only a faint ring of dampness remaining around the mouth of the skin. By dawn of the fifth day, the outer wall of the waterskins was as dry as a fired coarse-clay jar; even touching it carried a moisture-wicking dryness that clung to the hand; the moment a palm pressed against it, one could feel the skin’s moisture being drawn away toward an invisible direction.

No one in the column complained, but every person’s movements were half a beat slower than when they had first set out. Not fatigue -- they had walked longer distances in the West Bank settlement, at White River Ford, Wheat Hill Town, and Red Rock Slope -- but something else: when a person gradually loses every familiar reference point, the body reacts before the mind. Roadside vegetation vanished, the river’s humidity vanished, the cloud cover overhead vanished -- and in the end, even the color of the stones on the ground was vanishing. The world was shifting from an inhabited river valley into a blank map without a single marker.

On the third evening, when making camp, Kamon deliberately shifted the water-storage jars from the middle of the column to the very front -- not because they were short of water, but because he knew that once people realized they were getting farther and farther from the river, their throats would begin to feel dry earlier than the body actually required. This kind of thirst was not physiological -- it was psychological: when the eyes could not see the glint of a water source, the brain would issue a preemptive dehydration alert. He tied the jars’ palm-coir cord to the most visible spot on his cart shaft, so that anyone in the column had only to lift their head to see the outline of those clay jars -- seeing them was enough; seeing them, no one would panic.

On the fourth day, while checking the station map at noon, Meru discovered that pressing on another half day along the original route would bring them into a stretch of desert plain with absolutely no natural cover -- no trees, no rock faces, nothing to block the midday sun. He spread the map across his knee to show Lu Zhu and pointed to a fan-shaped blank zone he had circled in charcoal: ”From here to the cliff edge, direct distance roughly twelve li. Within those twelve li, there is not a single object taller than a man to cast shade. Marching this stretch at noon, the ground temperature will make the water inside the skins hot enough to scald the mouth.” Lu Zhu looked at the fan-shaped blank on the map and was silent a moment. ”Move tomorrow’s departure forward to one watch before dawn -- cover the most exposed stretch while the sun has not yet baked the ground hot. Tomorrow when everyone rises, no torches -- torchlight deceives the eye into thinking the sky has already brightened, when in fact the ground temperature has not yet begun to drop. Walk by starlight, and do not stop to rest until you can clearly see the tops of your own feet. Also, take down all the spare coarse linen from every cart -- soak it through tomorrow before departing, issue one piece to each person to drape over the head. It is not for cooling -- it is to block the heat reflecting upward from the ground.”

On the fifth morning, the caravan set out before the starlight had fully faded. The stars of early dawn were cold and sharp -- Orion hung low in the south, Sirius in the west, in the direction of the Nile, flashing a blue-tinged white light, slowly being diluted by the gray-blue sky glow spreading from the east. The air was icy; at the moment of departure, everyone’s coarse-linen tunics still held a trace of the faint dampness accumulated through the night -- the last time this wilderness would touch any form of moisture for the rest of the day. The eastern skyline shifted its colors in a manner impossibly slow yet irreversible: at first the entire arc was a uniform deep gray-blue; then the segment hugging the horizon suddenly brightened one level -- as if someone below had lit a wick of almost microscopic thinness; then that bright arc transitioned from gray-blue to cold white, and again to fish-belly white; and finally, at the very limit where it met the sand surface, the first ray of gold-red light burst through. The entire process took less time than it would to boil a pot of barley porridge.

Once the sun fully rose, the air was as though someone had lit a fire from below. The fine sand of the ground began to radiate heat upward -- not the heat coming down from above, but a second path of heat rising from beneath the soles: the solar heat the ground surface had absorbed during the day was now conducting upward through the spaces between the sand grains. The wooden rims of every cart in the column grew so hot one dared not touch them with bare hands -- Meru experimentally pressed his palm against his own wheel and, pulling his hand back, looked at it: his palm had been seared with a red line running across its width, the exact shape of the wheel rim’s wood grain. Mery draped across the back of his neck a strip of linen that had been soaked before departure -- the cloth went from damp to half-dry to bone-dry in less than half a watch. He took it from his neck and held it to the light; the fabric’s original woven texture was now packed with a layer of extremely fine white powder -- salt crystals left in the fiber gaps after the sweat evaporated.

Seb walked on the column’s left flank, his eyes narrowed eastward for a long stretch. Abruptly he turned his head and said to Kes beside him: ”That horizon line ahead -- it is not level. It tilts southward.” Kes followed his gaze and only slowly nodded after looking for a long while -- it was not a tilt the naked eye could discern at a glance. Eyes long accustomed to reading cross-sectional drawings had unconsciously caught a subtle discrepancy that a normal person would never notice: the mirage-light arc, bent upward by the heated air between the horizon and the eye, showed a difference in offset between the phantom image and the true ground surface along the north-south axis. This meant that the desert plain directly ahead, seemingly absolutely level, actually possessed a natural surface gradient that was not zero -- it was an extraordinarily gentle, almost imperceptible slope tilting southward.

The caravan marched on nearly two more watches. The sun climbed from the edge of the eastern cliff to a point just past the zenith, the human shadows shrunken to below the ankles, the edges of the wheel ruts pressed into the sand already beginning to crumble slightly. At the very front, Kamon suddenly raised his right hand -- his palm open, five fingers held together motionless. This was the most concise and least negotiable of the marching hand-signals the caravan had used for over three months: all personnel halt.

The entire caravan came to a stop in a gradually cascading series of creaking wooden axles. Kamon stood at the precise point where the last low stone ridge of the gravel plain tailed off -- the ridge at his feet was like an old wall foundation buried in sand, extending westward less than fifty paces before vanishing entirely beneath the sand layer. He stood at the ridge’s highest point, looked forward for one breath, then turned his head to glance at Lu Zhu. He did not need to speak. His expression had already said it for him -- behind them, no more reference points. Ahead of them, none either. From this point on, they had truly stepped onto the skin of a desert with not a single crease.

Lu Zhu rose from the cart shaft and used the back of his hand to shield his brow-bone from the sun. He gazed for a very long time -- not looking at any single point, but sweeping his entire field of vision from near to far, east to west, in one complete pass. The sunlight on the desert plain in the morning was white-leaning, not the golden, water-vapor-laden light of the river valley -- white light flattened every minute undulation on the ground, making the whole wilderness appear flatter, more docile, than it truly was. This light could deceive -- and Lu Zhu knew it well. The hard crust that formed on the soil surface after sun-baking, under strong light, looked no different from a rock foundation. But beneath was another matter.

He drew his gaze back and settled it on the flat expanse at his feet, a land not yet divided by a single corner of wall, a single enclosing fence, a single artificial drainage channel.

”Here we are,” he said. The voice was not loud, but Mehptah, standing on the cart frame behind him, heard it -- what he heard was not the literal meaning of those two words, but the extremely slight, deliberately flattened certainty pressing at the base of Lu Zhu’s throat as he said them.

This was the outlying wilderness of the new capital, Akhetaten. The new city site designated by pharaoh lay at the very center of this vast desert plain -- east of the Nile, open to north and south, flanked east and west by low limestone cliffs that served as natural windbreaks. The site itself posed no problem: near the river, on flat terrain, with cliff faces on two sides blocking the wind. The true hidden danger was not in where it sat -- but in what lay beneath.

The caravan made camp at the edge of the wilderness. Lu Zhu did not have anyone unload -- he told Kamon to keep the main artisan force at the camp to rest for half a day, while he himself took his four apprentices and Mehptah to the very center of the wilderness to conduct the first field survey. Before departing, he said one thing to Mery: ”Bring the foundation elevation-difference chart from the West Bank official granary. What we are measuring today is not the settlement of one building’s foundation -- it is the settlement of an entire city.”

When the party set out from camp, the sun had already risen to roughly three pole-heights above the cliff edge. The heat on the wilderness had begun to steam upward from the ground -- not the muggy, moisture-laden heat of the river valley, but pure dry heat, so dry the air drawn into the nostrils felt as rough as baked sand. The fine dust kicked up by each person’s footsteps formed a low tail behind them -- the dust was too light; once disturbed, it did not immediately fall back to the ground but spread through the air in a slowly churning pale yellow cloud, taking more than a dozen paces to fully dissipate. From a distance, the seven men looked like minute black silhouettes deployed in a line across the wilderness, each carrying measuring cords, sample tubes, charcoal sticks, and palm-fiber paper -- no carts, no horses, no guide markers. Aside from the row of footprints they themselves left behind, the entire wilderness held no artificial mark whatsoever. These seven tracks of footprints were the very first survey lines ever drawn upon this plot of earth.

Mery walked on the flank closest to the Nile. His assigned sector was the western edge of the entire planned area -- that is, the building sites that would in the future be nearest the riverbank. The moment he stepped into this zone, he sensed that the hard crust underfoot bore some inarticulable resemblance to the riverbank land on the outskirts of Wheat Hill Town. Wheat Hill’s crust had been naturally compacted by long-term soaking and sedimentation of river silt; the edges of its cracks, when magnified, revealed clear stratification -- a layer of silt, a layer of fine sand, another thin layer of clay sorted by water, like a book pressed flat. The crust on the wilderness, at first glance, appeared to be the same structure, but after he crouched and used his knife tip to scrape laterally, exposing a revealed cross-section, he found one critical difference between the Wheat Hill crust and the wilderness crust: Wheat Hill’s silt layer was mixed with green vegetal rotted roots -- remnants of riparian wetland vegetation. The wilderness silt layer also held rotted roots, but they were black, and their cross-sections were more fragmented -- these roots had rotted through in a far more ancient era, and the hydration process from being soaked in groundwater for untold years had corroded all the organic fibers into a gel-like mass susceptible to secondary deformation under pressure. Kneeling beside that shallow trench, he recorded in charcoal on paper: Western-edge silt layer organic-matter decomposition degree exceeds Wheat Hill by thirty percent; rotted-root fiber structure has been destroyed by hydration; compression rate under loading predicted to be more than double that of the Wheat Hill stratum.

He planted this marker in the earth and raised his head to look north -- that direction was the projected site of the future palace district. From where he now knelt to that slightly raised platform to the north, the terrain appeared continuous and level to the naked eye. But he moistened a finger with a drop of water and tested the wind direction against his lips -- the wind was moving from north to south, hugging the ground surface. On this type of ultra-flat alluvial plain, near-surface wind direction reflected the long-range slope direction of the ground with considerable fidelity: air moving against the surface would slide toward the lower ground along the natural surface’s extremely gentle gradient. This slope, across visible distance, betrayed no discernible elevation difference -- yet it truly existed, and its direction, from north to south, ran roughly parallel to the Nile’s flow. This meant that even disregarding groundwater, surface runoff alone would channel all rainy-season accumulated water toward the southern wing’s storage district. He added this wind-direction observation below the cross-sectional drawing -- a natural gradient invisible to the naked eye, one that would play a decisive role in the initial planning of the entire city’s drainage system.

Seb’s position was in the east-central section of the planned area -- his assignment was to survey the hard-crust layer’s uniform thickness and the distribution of subsurface cavities. He carried a palm-fiber measuring cord that Lu Zhu had temporarily extended just before departure -- two extremely thin stone flakes were affixed to the cord’s crossbar, their edges ground into blunt hooks, capable of reaching into soil-layer crevices to retrieve specimens from different depths without having to excavate the entire cross-section. This tool was something he had modified himself from scrap stone flakes found in camp after using it once at Wheat Hill; it had no formal name; he called it the ”mud-probe hook.”

The third time the mud-probe hook was inserted from the surface, it hooked out the data he needed. The hard-crust layer’s thickness across the entire central zone was not uniform -- he took measurements at seven points on the same platform. The crust thickness was at its thinnest less than three finger-widths, at its thickest exactly five finger-widths. This three-finger-width difference was entirely imperceptible from the surface -- because walking on it, the tactile sensation underfoot was the same -- but this three-finger difference meant that the bearing capacity of the silt layer beneath would produce seven entirely different load responses at these seven points. He drew a point chart on palm-fiber paper, each point annotated beside it with its crust thickness, silt-layer depth, and the particle size of the underlying sand. The particle-size data came from temporarily screening with a wooden-frame sieve -- he poured the bottom-sand samples taken from the seven points one by one into the sieve and shook it several times to see the proportion of different grain sizes retained on the screen surface. The screening results of the seven samples told him: the sand layer one to two cubits below the surface in the central zone was fine-grained, the particle-size distribution concentrated within an extremely narrow range -- typical characteristics of wind-deposited sand. But further down, beyond three cubits, the sand grains abruptly coarsened, and a set of rounded cobblestones appeared, stones clearly not belonging to this plane -- these were alluvial deposits transported by an ancient river channel, their age far older than the overlying wind-deposited sand. There was no gradual transition between the two depositional sets -- meaning a massive river-course diversion had occurred between these two eras.

He marked the comparison result of these two data sets as ”Dual-Source Superimposition” -- the upper layer formed by wind, the lower by water. In the future, any structure built on this zone exceeding the weight of a single-story dwelling would require foundation piles driven through the wind-deposited sand layer to the alluvial gravel surface -- otherwise the upper half’s wind-deposited sand, after the load fractured the hard crust, would undergo wholesale settlement.

Kes was assigned to the northern zone near the cliff face; his task was to determine the tilt direction and seepage path of the groundwater table. He spent a full watch on his assigned sector, successively opening six shallow test bores -- not with an iron spade, but by rotating and pressing down a thin bamboo tube. The bamboo tube was a method he had learned on the outskirts of Wheat Hill Town: sharpen one end of the bamboo tube, then use body weight to press and drill it downward. Drilled to a certain depth, yank the tube out fast, and inside the tube would come a complete segment of the subsurface soil column, the moisture content and color of each layer visible at a glance.

Of the six bores, the one nearest the cliff encountered saturated water at a depth of three and a half cubits -- the inner wall of the extracted bamboo tube was beaded with strings of water droplets, the lower edges of the droplets connecting to wet mud, the mud’s color graduating from the surface yellow-white to pale gray to deep black, the transition layer completing within less than a cubit of depth -- indicating that the capillary rise height near here was at least half that of a normal alluvial plain. In the three bores heading toward the Nile, the saturated-water layer’s position deepened in sequence -- the fourth bore’s saturated layer reached five cubits deep, the fifth exceeded six, and the bore nearest the river, the bamboo tube entirely expended at seven cubits, still had not touched a fully saturated layer -- only the lower section of the tube bore a film of damp mud, the salt efflorescence crusted on the mud surface visibly thicker and whiter than that in the northern bores. The water-level line connected from the six bores’ data yielded a groundwater tilt direction that ran precisely from the riverbank inland, from west to east gradually shallowing -- not the reverse. This meant that the future groundwater recharge direction on the wilderness was infiltrating inward from the Nile, a completely different model from the east-to-west flow he had observed at the West Bank settlement. He compared the six-bore data against the regional geomorphological sketch Lu Zhu had given him the day before and drew, on the spot, a set of water-table contour lines -- every contour line curved densely toward the direction of the eastern cliff face, indicating that the foot of the cliff was the location with the shallowest groundwater table across the entire wilderness. If the palace were to be built on the high ground west of the cliff face, the threat of the groundwater table to the foundation would be more severe than if it were built beside the riverbank -- because the groundwater, percolating over from the river surface, had already traveled three li; along the way there was nowhere to drain, nowhere to evaporate, the entire volume accumulating in the low-lying silt layer at the base of the cliff -- a natural catchment basin, merely concealed beneath a layer of hard crust invisible to the naked eye.

Mehptah barely opened his mouth during the entire survey. He used no measuring cord, sieved no sand, deployed no mud-probe hook, sank no bamboo-tube well. But his eyes were doing something else -- he had been watching, the whole time, the relationship between this entire wilderness and the rock strata outcropping discontinuously at various heights around it. He was a quarryman, and his way of looking at ground was essentially no different from his way of looking at a rough block. When a block of stone was set before him, the first thing he did was not measure its dimensions -- he read where its grain started, which turning point it passed before beginning to change direction, where it ultimately stopped. This mode of observation had, without his conscious intention, been transferred from stone stock to the entire wilderness.

What he noticed first was the limestone outcrop at the foot of the eastern cliff on the wilderness. The bedding-plane dip of the limestone was near horizontal -- barely five degrees -- but the fracture orientations etched into the cliff face by wind and rain erosion were not random: every fracture extended flat and straight toward the west -- that is, toward the river. These were not natural fractures -- somewhere below the limestone layer was a set of uneven subsidence zones, pulling the overlying rock strata westward into a visible but extremely small-amplitude array of tilted fissures. If this tilted-fissure array were projected upward to the ground surface -- that is, onto the surface sediments of the wilderness -- its position, barring accident, would pass directly through some spot near the very center of the future city’s central axis.

He walked back to find Seb and, pointing at the fracture orientation on the cliff face, said one sentence: ”Those subsurface cavities you dug up -- mark their positions on the ground. Then extend each cavity half a cubit to the southwest and connect them into a single line -- that line is the surface projection of the subsidence fissure where the limestone zone beneath the cliff tilts westward. In the future, when any building on the central axis crosses this line, the joints between the drainage channels and the foundations must be specially reinforced -- not against water, but against the two halves of the stratum above and below this line shaking in different directions during an earthquake.”

Lu Zhu had noticed Mehptah’s movements. He did not interrupt the old quarryman’s conversation with Seb, but stood a few paces away, listening quietly -- he was listening to a man who had read stone with hammer and chisel for forty years, using a method that deployed no quantitative measurement tools whatsoever, produce a geological conclusion that would require hundreds of survey points, dozens of cross-sections, to back-calculate from data. The precision of this conclusion would need subsequent survey bores to verify -- but its direction of insight was accurate. Before anyone had drawn the central axis of an entire city onto paper, someone had already traced its foundation risks one whole layer deeper, to their bedrock origins.

The survey lasted nearly two full watches. The midday sun beat directly onto everyone’s heads; the fine sand of the wilderness was bleached white by the heat, hot air steamed upward from underfoot, baking everyone’s trouser legs into stiff shells. Kes and Seb, separated by roughly three hundred cubits, used hand signals to exchange their respective saturation-depth data. Mery lay prone at the far western end, that strip of riverbank lowland, completing his map of the silt’s longitudinal texture gradient. Mehptah crouched at the hard-crust edge, scraping down one last salt-efflorescence sample -- an old quarryman from the Thebes quarry, encountering saline-alkaline ground, never tested with water -- water could deceive; the tongue could not. He scraped three samples separately: one near the riverbank, one in the center, one at the cliff base, intending to compare their alkalinity differences by burning them back at camp.

Lu Zhu walked no fewer than five round trips between the sectors his three apprentices were each responsible for. Each time he reached the shallow pit Seb had dug, he would glance at the moisture-content variation in the silt; then walk to the bamboo-tube survey point Kes had set up, cross-checking the mud color at each section of the tube’s inner wall against Seb’s cross-sectional data. He was doing something that had become habit along the road: taking data from different sources, different methods, different depths, and placing them on the same plane to verify each other. Seb’s data was lateral-distribution thickness variation; Kes’s data was longitudinal-distribution water-level variation; Mery’s data was textural variation. These three data sets were originally unaffiliated with one another, but Lu Zhu’s every back-and-forth stride across the middle was an attempt to find a single complete subsurface model that could simultaneously accommodate all three.

It would be impossible to complete this model from today’s survey alone -- the data was still insufficient. But he could already see its outline.

The experience of stepping into the wilderness was entirely different from marching along the Nile. However barren the riverbank, there were always palms and reed thickets -- but the wilderness had none. Underfoot lay a surface crust of dried floodplain, its surface laced with countless fine desiccation cracks, looking flat and hard to the naked eye but splitting under a single stomp. Seb walked less than two hundred paces before crouching down and digging open that patch of cracked surface crust beneath his feet -- less than half a cubit down, he struck a layer of dark-colored silt. Below the silt was an interbedded structure of fine sand and clay in alternating layers.

The color of that silt was not the gray-green of fresh deposits that had only seen one or two years of flooding -- it was a near-black deep brown, mixed with rotted vegetal fragments whose fibrous structure was no longer discernible, the fragment edges blurred beyond recognition by water-soaking, the texture under kneading somewhere between clay and gel, sliding out between the fingers at the slightest pressure. This meant that in some distant era, this area had been an old riverbend of a former Nile channel -- not seasonally submerged by flooding, but a riverbed bottom submerged year-round over long ages. After the old riverbend had been abandoned in the center of this wilderness by some later channel diversion, the water above had slowly evaporated and receded, but the silt below had never dried -- it had been pressed down by one new layer after another of wind-deposited fine sand over thousands of years, forming a kind of naturally occurring confining layer, the moisture in the silt compressed within, unable to drain downward or laterally.

He used the palm-fiber measuring cord to gauge the crust thickness and recorded a line of data on palm-fiber paper: Hard-crust layer approximately four finger-widths thick, underlain by silt interbedded with fine sand, distribution continuous.

”This land is called ’hard crust’ -- but that is just the sun-baked surface. Beneath is the old alluvium of a former Nile channel -- silt alternating with fine sand, the same type as the soft foundation under the wheat fields on the West Bank. But worse -- over on the West Bank, at least near the riverbank there is a natural drainage gradient. Here, it is flat. Drainage has nowhere to go; the water is all trapped in the mud layer.”

His judgment was progressively confirmed, point by point, by the measured data from each sector over the next half-watch. Uneven hard-crust thickness, groundwater table shallowing from west to east, alkaline-salt reflux paths penetrating the entire silt layer -- the three core hidden hazards took shape under charcoal in succession.

Mery measured the longitudinal textural gradient of the silt layer at the western-edge low-lying profile. From the riverbank margin inland, he took one mud sample every twenty cubits and arranged them in a neat sequence on palm-fiber paper. The sample nearest the riverbank -- that is, the position closest to water -- was a reddish brown-gray silt, high in sand content, the fingers upon kneading detecting an evident gritty sensation of sand grains, indicating that the Nile during its flood stage carried coarser river sand to this position. Moving sixty cubits eastward, the second sample’s color had already shifted to gray-brown, the sand grains markedly fewer, replaced by a slick, exceedingly fine clay-particle sediment so smooth it could nearly be smeared evenly across a finger -- this was the kind of deposit that only precipitated under prolonged still-water conditions, showing that this portion of the silt layer had not accumulated during flood stage but had naturally settled from suspension when the ancient river channel existed as a stable water body over a long duration. After walking a hundred cubits, the third sample’s color was near deep black, the clay content so high that scraping it with a fingernail produced raised extrusion rims on either side of the scrape -- a classic characteristic of high-plasticity clay. The gradient direction of the three samples matched the cut-bank direction of the ancient Nile channel; the highest clay-content point in the silt layer, unexpectedly, appeared not near the riverbank but nearly a hundred cubits removed from it -- indicating that the ancient channel’s base at this point was a relatively enclosed shallow-basin landform, where clay accumulated after suspension settlement without dispersing outward.

Seb continued digging deeper in the central zone -- at roughly two cubits down, his hand suddenly stopped. The spade’s tip under his hand had struck a hard surface -- not stone, but something else: a layer of dark-colored clay compacted to extreme density, the clay internally studded with countless, regularly arrayed minute calcium-carbonate nodules. These nodules were astonishingly uniform in size -- nearly all distributed between mung-bean and soybean dimensions, their shapes irregular spheroids, their surfaces polished smooth by water. The formation of such calcium nodules required two conditions: the groundwater table repeatedly fluctuating within small amplitudes at a certain depth, and the soil solution being rich in calcium ions. The nodule layer was extensive in area -- Seb dug fifty cubits east and fifty west to verify, and the nodule layer was present continuously at every point, only beginning to thin and scatter near the cliff base. He stood, planted his iron spade in the earth, and shouted toward Lu Zhu, who stood guard at the distant shallow pit: ”This nodule layer formed from the groundwater table of some past period oscillating repeatedly at a single stable height -- that height is exactly the lower boundary of the silt layer beneath the hard crust that I measured earlier. The position of the nodules is the upper limit of the average groundwater residence level. If, after the city is built, the groundwater table is raised by more than one cubit overall due to artificial irrigation and domestic drainage, the nodule layer will re-dissolve -- the entire silt layer of the central city zone will regress from a nodule-cemented stable state to a saturated mobile state.”

Everyone understood the weight of this warning. Seb was not normally a talker; at Wheat Hill Town he could go an entire day without opening his mouth, just drawing. At Red Rock Slope he could kneel on a rock pile sieving sand samples all day without eating. But every time he spoke a complete sentence of more than ten words, it was always because the discovery had touched a very specific risk boundary within his cognitive system. The dissolution of the nodule layer meant the groundwater table had already been raised as a whole to a new height -- the foundation’s stability conditions would undergo wholesale drift as a consequence.

Kes, at the northern position near the cliff face, excavated yet another profile -- this time what he dug up was not silt, not fine sand, not calcium nodules, but a sedimentary layer mixed with limestone detritus and weathered dolomite powder. This sedimentary layer’s elevation stood nearly a cubit above the silt layer, its color a pale gray-white, its texture so loose it could be squeezed completely into a fist -- yet when the fist was opened, it did not flow away like sand but held the squeezed shape for a short while before cracking apart. This rebound-time differential in shape retention indicated that the sedimentary layer contained some trace cementing component -- possibly a chemical precipitate of siliceous fines at a specific pH, or possibly a semi-soluble-phase product of dolomite weathering. Either way, the engineering implication was the same: this sediment, when dry, possessed a certain structural strength, but once saturated with water, the cementing agent would rapidly dissolve and wash away, and the entire soil mass would degrade from a structural layer into an uncemented granular mass. If the palace district were to set its foundations at this elevation, the foundation-base elevation could not be dropped by a single inch -- dropping one inch would punch into this ”false-cemented” layer; every dry season it would behave like stone, every rainy season like rotten mud.

Lu Zhu set the silt samples on the edge of the shallow pit and had Kes draw, at the same position, the wilderness’s first structural sketch of a subsurface alkaline-barrier layer -- a flat layer of coarse crushed stone, with extremely thin dolomitic limestone powder packed into the stone crevices at mid-depth, a layer of coarse palm-fiber netting on the top and bottom faces, and an additional thin waterproofing layer clamped on both sides. This structure was something Kes had never seen in identical form on any building cross-section along the road -- it was an answer that had assembled itself spontaneously from Mehptah’s tongue, Lu Zhu’s new capital plan, and the drainage vertical-section drawings Kes himself had made along the middle-reaches river valley, three mutually foreign knowledges placed in the same mud pit.

Lu Zhu placed the silt sample on a cloth and stood, gazing eastward. From here to the direction of the new capital’s planned central axis -- there were still nearly a thousand cubits to go. The vast wilderness before his eyes was utterly different from the foundation plots he had leveled back at the West Bank settlement: back then, the hidden hazards had been mostly in the surface rubble heaps and drainage-ditch depths -- but here, every inch of soil concealed three great dangers: uneven hard-crust thickness, groundwater levels shallowing from west to east, and alkaline-salt reflux paths running the full length of the silt layer. Any one of them could be resolved by localized reinforcement -- but with all three hazards simultaneously present beneath the same foundation, this was no longer a question of how much stone bedding to add. What they demanded was a fundamental restructuring of the entire city’s spatial organization -- which building types belonged on which geological zones, how the arterial roads and main drainage channels should exploit the natural tilt direction of the groundwater, whether the central axis alignment needed localized deflection where it crossed geological risk bands. These decisions had to be made before the first block of stone was transported onto the worksite.

He stood in the center of the wilderness, his four apprentices each crouched at different survey points around him -- Mery at the far west end, on the riverbank lowland, separated by nearly five hundred cubits, visible only as a tiny outline crouched on the mud, the palm-fiber paper on his knee fluttering upward in the wind as he pressed down its edge with his other hand to keep the data from being snatched away. Seb was at his excavation pit in the east-central zone, his iron spade thrust vertically into the sandy soil beside the pit, the blade’s reflection flashing in bursts toward the camp -- the signal-code he had arranged with Kes, two flashes meant depth data matched prediction, three flashes meant deviation exceeding half a cubit. Kes was at the northern cliff base, bamboo tubes and sample canisters arrayed in a row on the stone ridge beside him; every few paces he crouched, raised a sample canister to the sunlight, and compared the color gradation of the mud. Four people, four directions, four scales of observation -- every data set pointed to the same plot of earth, yet each data set saw a subsurface world not entirely identical to the others. He, standing at the center, had to integrate all four perspectives into a single cross-sectional drawing -- not by averaging them, nor by favoring whichever data was more reliable, but by finding the intersection point where all four data sets corroborated each other at a certain number of cubits below the surface. Once that intersection was located, the spatial layout of the entire new city would possess a measurable common starting point.

When the end-of-work call sounded from the camp, the sun had already slipped behind the western cliff. The last direct ray of sunlight on the wilderness squeezed through a crevice between two massive boulders at the clifftop and brushed a golden band of light, no wider than a palm, horizontally across the entire desert plain -- that band stretched from the cliff base all the way to the Nile’s bank, dragging a diagonal shadow that crept steadily northward across the sun-baked hard-crust surface. From a distance, the seven people walking from the center of the wilderness back to camp passed through this fading band of light one after another -- first Mery, his head still lowered over that silt-texture gradient map, the light-band dragging a shadow longer than his own body from his back; then Seb and Kes, their arms each cradling a bundle of mud-stained sample canisters and bamboo tubes; then Mehptah, the old quarryman’s pace slower than the young ones, but as he crossed the light-band he deliberately paused one step and turned his head to look westward -- there was the Nile, traces of wind on the river surface; last of all, Lu Zhu, who wrapped the stack of drawings in his arms with a layer of coarse linen, then bound them tight with a palm frond -- reaching the end of the light-band, he raised his eyes and looked toward the eastern cliff; the cliff was no longer the sun-bleached limestone white of the day but stained a dull red-brown by the sunset striking it from the other side -- that glance was not to admire scenery but to confirm one thing: the width of the shadow zone at the cliff base, measured against the endpoint position of the first station of the ”profile test-pit along the cliff tomorrow” he had described to Seb that afternoon, was separated by approximately half a watch’s walking distance.

When they returned to camp, the sky had already darkened enough to need torches. Kamon had led the artisans in erecting temporary work shelters at the wilderness’s edge -- the shelter roofs were lashed with coarse palm-fiber cord and covered with a layer of linen shelter-cloth taken down from the carts. The ground inside the shelters had not been spread with any covering -- on the wilderness it was impossible to find wheat straw or dried grass -- everyone’s bed tonight was a coarse linen mat laid across their own tool case. The campfire burned in the open ground at the camp’s center; the firelight illuminated the faces in a circle around it: red, yellow, flickering, and on this early night with the wind blowing from the north, every face’s pattern of light and shadow seemed nudged gently southward by an unseen hand and then spring back. The evening meal was dried barley cakes boiled in water with a few strips of sun-dried river fish -- the cakes crumbled into the copper pot’s hot water and stirred into a paste, the dried fish torn into fine bits and scattered over the surface. Mery tossed a small pinch of the rock salt he had brought from Wheat Hill Town into the pot bottom; the salt grains striking the surface of the boiled barley paste made an extremely faint sizzling sound, then dissolved swiftly. No one spoke -- not from being too tired to speak, but because everyone’s mouth was packed full of that portion of the survey data they had had no chance to finish digesting on the road. Mery, stirring the paste in his bowl with a wooden spoon, was simultaneously retracing that silt longitudinal-gradient chart on his palm-fiber paper -- his left hand holding the bowl, right hand pinching the charcoal, eyes fixed on the three sample-point elevation marks on the paper. Seb sat on a low stone slab across the fire, the half-dried draft of his cross-sectional drawing laid across his knees -- he had already marked the calcium-nodule layer section with double-line blocks, but the transition segment extending outward to the cliff base still made him hesitate over what symbol to use for that layer where the nodules gradually thinned and dispersed.

Lu Zhu did not eat supper -- he pushed his portion of the barley paste to the edge of Mery’s bowl, then drew from inside his tunic the composite sketch he had made on the wilderness that day. By the leaping light of the campfire, he spread it across the flat stone he had carried all the way from the West Bank to use as a drawing board. This flat stone was something he had picked up at White River Ford from the steps of an old ferry landing collapsed by flood -- the stone face had been trodden by countless feet, worn smooth as bone, bearing the faint milky-white polarized sheen unique to limestone. From that day on, he had kept this stone in the lowest compartment of his cart, taking it out as a work surface at every station where they made camp.

On the flat stone he laid out the four sub-diagrams in sequence. The first was Seb’s soil-layer thickness distribution map of the central zone -- spatial variation of hard-crust thickness marked with varying densities of diagonal hatching. The second was Kes’s six-bore groundwater-table contour map -- the contours bending densely toward the direction of the natural catchment blind-ditch at the cliff base. The third was Mery’s silt-texture longitudinal-gradient map -- from the riverbank eastward, the silt’s sand content decreasing as clay content increased. The fourth was the rock-fissure projection map that Mehptah had described orally and Seb had transcribed onto paper for him -- a diagonal line extending from the cliff face to slightly west of the wilderness center.

He transcribed the core data from all four diagrams onto a single new sheet of palm-fiber paper, using charcoal. This was not simple copying -- every data point he transferred, he cross-verified against the data at the corresponding position on the other three diagrams. Seb’s hard-crust thickness figure decreased near the riverbank -- did Mery’s silt clay-content at that position simultaneously increase? It did increase -- meaning the two facts corroborated each other: near the riverbank, being the lateral margin of the ancient channel, the hard crust had been scoured thinner by hydraulic force, but the underlying sedimentary clay was conversely thicker. Kes’s groundwater table shallowed to less than three cubits at the cliff base -- did Mehptah’s fissure-projection line happen to pass through this shallow-water point? It did, and the fissure orientation ran perpendicular to the curvature direction of the water-table contours -- meaning the groundwater convergence direction was indeed controlled by the fissure zone.

He drew a long longitudinal profile reference line on the paper -- from the cliff face to the riverbank, total length nearly twelve hundred cubits. Then along this reference line, from top to bottom, he sequentially annotated the three core hazards: hard-crust thickness variation, groundwater-table depth curve, alkaline-salt reflux path. Once the three data sets were sequentially arrayed along the same profile’s longitudinal axis, a geological cross-sectional model, entirely invisible from the surface but below ground clear to a nearly three-dimensional degree, was slowly materializing under his charcoal.

In his mind, he re-sorted the day’s survey priorities: the first thing to resolve was not drainage, not foundation depth, not the alkaline-salt barrier -- the first thing to determine was the geological positioning line of the entire central axis. The central axis had to avoid the cliff-fissure projection zone, had to lie on the favorable side of the groundwater-tilt direction, had to pass through the longitudinal belt where hard-crust thickness was most uniform -- the linear interval that simultaneously satisfied these three constraints was only one, its width not exceeding eighty cubits. Laying out the central axis within this eighty-cubit-wide corridor would allow it to serve as the spinal column of citywide planning, hanging every other district on the most stable foundation. If it deviated from this corridor by a single step in any direction, the central axis would at some segment cross into the fissure zone, or press onto thin-crust beds, or sit directly above the groundwater convergence blind-ditch -- and then any local deformation would, due to the central axis’s continuous nature, amplify across the entire city.

He wrote this conclusion at the very top line of the profile drawing, the characters almost half their usual size -- not because he wanted to obscure them, but because his hand, in writing this conclusion, controlled the stroke pressure with extreme caution. This line of text would determine the geometric origin point of every building in the new capital. After writing it, he pressed the pad of his finger lightly over the characters -- not to set the charcoal dust, but to confirm that the position of this line of text had left enough room below for annotating all the second-tier subdivision data.

The camp’s fire gradually shrank in the night. Kamon beside it used sand to smother the outermost embers and glanced toward Lu Zhu -- Lu Zhu was still drawing something on the flat stone, but the fire was nearly out. He pulled from his cart a spare length of old cord-end soaked in palm oil and laid it on a piece of charcoal at the fire’s heart that still held residual heat -- the moment the flame surged back to life, its light swept across Lu Zhu’s flat-stone drawing board, illuminating with perfect clarity the cross-section of old drawings beneath three or four layers of accumulated charcoal dust on the stone’s surface. What Kamon saw, on the stone face, were strata of fresh and old charcoal powder like sedimentary sequences in geological strata -- each layer a grade of ash not yet dry, pressed down atop the last; each layer a cross-section traced from the West Bank refugee settlement to this day, still not fully annotated.

The temperature plummeted fast in the deep night. The wilderness that by day could bake a waterskin hot enough to burn the hand, by midnight saw the fine sand of the ground surface rapidly dispersing outward all the heat it had stored through the day -- the cold did not descend from above; it rose from below. Beneath everyone’s linen mat, the floor sand layer was perceptibly cooling -- a cold that was not the dank chill of moisture but a dry cold, so dry the throat would involuntarily press the mouth shut once deep sleep set in. Lu Zhu lifted the last completed central-axis positioning map from the flat stone and laid it flat beneath the lid of the tool case at his bedroll -- after weighting it down, he pulled an extra piece of coarse linen from his cart, draped it over himself, and closed his eyes.

Behind his eyelids, in the darkness, the day’s survey data continued assembling. He could feel his brain had already organized all the day’s observational data from his apprentices into an ordered set of cross-sectional frameworks -- the few profile connection points still missing from the framework would be filled in tomorrow, once the first set of test pits was sunk. He did not need, before falling asleep, to straighten out every misaligned line. He knew that at daybreak tomorrow, the first ray of morning light would first strike the top face of the eastern cliff -- the limestone there would whiten. And there he would begin sinking the first shallow bore.

(End of Chapter 10)