Devotional Speleology

[Images: Photo by BLDGBLOG].

I’ve been traveling around London, the Adriatic, and the Mediterranean Sea the past few weeks, doing research for a new book, and thus not really using the internet outside of a bunch of Instagram shots; nonetheless, I thought I’d post some pictures from the trip.

Here, above, is Nicola Twilley peering into an old devotional cave dwelling on the Marjan peninsula outside Split, Croatia.

[Image: Photo by BLDGBLOG].

The hermitage is up in a cliff behind a church dedicated to St. Jerome, and the whole complex apparently dates back to the 15th century.

The church itself is also quite picturesque among the trees, with a nearly panoramic view of the Adriatic.

See many more general travel shots on Instagram.

Subterranean Robotics on Other Worlds

pavonis-mons-skylight[Image: Possible cave entrance on Mars, via space.com].

There was an interesting article in last month’s issue of Air & Space about the design of subterranean robotics for exploring caves on other planets.

It primarily looks at “a robot called LEMUR, short for Limbed Excursion Mechanical Utility Robot.” LEMUR, we read, “is designed to climb the porous walls of a cave 150 million miles away, on Mars.”

lemur
[Image: The LEMUR robot in action; photo by Aaron Parness/JPL via Air & Space].

The article goes on to discuss the work of speleobiologist Penelope Boston, who you might remember from a long interview here on BLDGBLOG (originally recorded for Venue), as well as the challenges of sample-return missions, how robots might go spelunking on other planets, and more.

Check it out in full.

Schrödinger’s Speleology, or the Stalking of “Entranceless Caves”


[Image: A cave entrance in France, via Wikipedia].

I recently finished reading Last Words by Michael Koryta, a detective novel largely centered on an unmapped fictional cave system in southern Indiana, part of the great karst belt near the border with Kentucky.

One interesting thing about the novel is that this cave, known in the book as “Trapdoor,” operates on many different narrative levels. Most obviously, of course, there’s the unreliable memory of a major character suspected—yet never officially accused—of committing a murder there, where the darkness of Trapdoor’s linked subterranean spaces becomes a kind of mental model for his own inability to recall what really happened, when a woman was (apparently) murdered in the cave’s depths.

There is also a subplot, though, revealed quite late in the book, in which disguised real estate deals and obscure land trust deeds have been premised on the subterranean potential of this land snaking along the region’s old creeks and rivers, transactions inked with the belief that Trapdoor’s passages might continue beneath distant parcels; in this way, the cave comes to represent the conspiratorial intentions of people otherwise unwilling to state their true goals.

Finding the true outer limits of the cave—that is, finding the land parcels that the cave secretly connects from below—becomes coextensive with discovering the truth about what occurred underground there so many years earlier.


[Image: Cave in Venezuela, photographed by Vittorio Crobu, courtesy European Space Agency].

It was these latter parts of the novel—including a handful of plot points I won’t get into—that reminded me of notes I’d taken from a book called the Encyclopedia of Caves several years ago. That book includes a short entry written by Nevin W. Davis, called “Entranceless Caves, Discovery of.”

As Davis describes them, “entranceless caves” are like speleological versions of Schrödinger’s cat: they exist, but they have not been verified. They are real—but perhaps not. They are both in the ground and nowhere.

At times, Davis’s text is almost like a koan: “Suppose the cave is totally unknown and has no entrance,” he writes. What exactly is such a thing, and how can we account for its presence (or absence) in the landscape? After all, these are caves that have not been—and perhaps cannot ever be—located.

He goes on to describe mathematical models used to generate a probability of subterranean connection: the calculated likelihood that physically inaccessible voids might exist beneath the surface of things, linking one part of the world to another.


[Image: Cave in Mexico, photographed by Vittorio Crobu, courtesy European Space Agency].

“Another consideration in searching for caves,” Davis continues, “is entrance lifetime. Caves are long-term features under the landscape with lifetimes measured in millions of years, whereas entrances to them are fleeting features with lifetimes measured in millennia.”

Cave entrances come and go, in other words, while the caves they once led to remain. They can be covered over, woven shut by tree roots, erased.

As Davis describes it, “leaves and twigs will soon cover and block small vertical entrances. Pits less than a meter in diameter”—tiny holes that can nonetheless lead to huge systems, such as the real-life Mammoth Cave or the fictional Trapdoor—“can be totally blocked in one season. Leaves blocking a small entrance are soon followed by roots and more leaves and it is not long before all traces of an entrance are gone.”

This leads to an activity he calls “stalking the elusive entranceless cave”—which, for what it’s worth, seems like a perfect metaphor for part of Koryta’s novel, in which the book’s amnesia-stricken potential murderer undergoes hypnosis. His memory is a cave with no entrance.


[Image: Cave in Venezuela, photographed by Vittorio Crobu, courtesy European Space Agency].

In any case, there can also be “false positives,” Davis warns. These would be caves that appear to have been detected but that are not, in fact, real. A “stalker” of previously unknown caves might find herself misled by patches of melted snow, for example, or by other signs that wrongly give the impression of warm air rising from empty passages below.

“The best condition to search for snow melt,” Davis suggests, instead, “is with a new snowfall in midwinter with an overcast sky, since sunlight can also give false positives by shining through snow cover onto rocks and melting the snow. This is a tried-and-true method that has led to countless new caves.” It’s cave-discovery weather.

In essence, this is a process of reading the landscape: interpreting its surface features in order to gain knowledge of these other, deeper dimensions.


[Image: An artificially enlarged entrance to Carlsbad Caverns; Instagram by BLDGBLOG].

The next entry in the Encyclopedia is also worth reading; it is simply called “Entrances,” by William B. White. “Some caves,” White writes, continuing the strangely existential thread of Davis’s work, “may have no entrances at all.”

White adds a new category here, what he calls the “concealed entrance.”

At least from an architectural point of view, what’s interesting is that this allows White and other speleologists to challenge the idea of there being a clean dividing line between inside and outside, between a cave and the Earth’s surface.

Instead, he suggests, a cave’s entrance should actually be thought of as a transition: the “cave entrance zone,” White writes, “is, in effect, a continuous sequence of microclimates,” one that eventually leads to a point at which there is no direct access to sunlight or to rainfall.

It is only at that point that you are truly “inside” the Earth. You have transitioned to the great interior.


[Image: Photographer unknown; image via Discovery Communications].

Briefly, White also points out that cave entrances are not only unstable in the temporal sense—as Davis mentioned, cave entrances can completely disappear over time.

However, they are also unstable spatially: that is, they can physically migrate through the landscape over thousands, or even tens, of years.

Due to continual rockfall, for example, a cave entrance “not only migrates deeper into the hill but also migrates upward as rocks break away,” Davis writes. This can potentially push a cave entrance dozens and dozens of feet from its original location, while the cave itself remains stationary. Imagine a mouth migrating across your body while your stomach stands still.

Of course, this also means that an entrance to a given cave system can abruptly migrate onto someone else’s property, or that it can even pop open, suddenly and dramatically changing the value of a particular piece of land.

The next thing you know, following an unusually intense summer rainstorm, you own the entrance to a cave.

[Image: A salt cave in Israel; image via Wikipedia].

Which brings us back to Michael Koryta’s novel. There, an unexpected opening into the unstable depths of Indiana’s fictional Trapdoor complex changes the lives of many characters not just for the worse, but for the tragic.

The cave, as Koryta depicts it, is a relentless and unsympathetic thing, a space always shifting, growing organically but not alive, invisible yet ubiquitous, moving beneath the surface of the landscape, connecting parcels of land, as well as the lives—and deaths—of the characters who thought they were just idly passing time above.

(Vaguely related: Life on the Subsurface: An Interview with Penelope Boston).

The Voids Beneath

sinkhole[Image: Drone footage of a Cornwall garden sinkhole, via the BBC].

One of the peculiar pleasures of reading Subterranea, a magazine published by Subterranea Britannica, is catching up on British sinkhole news.

In more or less every issue, there will be tales of such things as “a mysterious collapse in a garden behind a 19th-century house,” that turns out to be a shaft leading down into a forgotten sand mine, or of “abandoned chalk mine sites” heavily eroding in winter rain storms, “resulting in roof-falls.”

“As most chalk mines are at relatively shallow depth,” Subterranea reports, “these roof-falls migrate upwards to break [the] surface as ‘crown holes’ or craters, which in the said winter [of 2013/2014] have been appearing in lawns and driveways, and even under houses, newly built in chalk districts.”

The earth deceptively hollow, the landscape around you actually a ceiling for spaces beneath.

Worryingly, many of these mines and underground quarries are difficult, if not impossible, to locate, as insufficient regulation combined with shabby documentation practices mean that there could be abandoned underground workings you might never be aware of hiding beneath your own property—until next winter’s rains kick in, that is, or the next, when you can look forward to staring out at the grass and shrubbery, with growing angst, waiting for sinkholes to appear. Rain becomes a kind of cave-finding technology.

Even in the heart of London, the underworld beckons. Last Spring, Subterranea reminds us, “a woman and her shopping trolley rather suddenly disappeared into a four metres deep hole in North End Road, Fulham.” The culprit? It “appears to have been a disused under-street coal cellar.”

Perhaps the most incredible recent example, however, comes from the town of Scorrier, in Cornwall.

shaft[Image: Photo courtesy The Sun].

There, a “deep mine shaft has appeared” beneath the patio of a house in the process of being prepped for sale. “The shaft drops approximately 300 feet deep to water but could be four or five times deeper [!] below that,” Subterranea reports. It “is a remnant of Cornwall’s tin mining industry in the 18th century.”

It is a straight vertical shaft, more like a rectangular well, yawning open behind the house.

And there are many more of these mines and quarries, still waiting to be discovered: “As mines closed,” we read, “many [mining companies] put very large blocks of timber, often old railway sleepers, across shafts and backfilled them, thinking this would be safe. Gradually all evidence of the engine houses and covered shafts disappeared from view and memory and in the past builders assumed there was nothing there. Had they consulted old maps they would have known about the shaft. The timbers rotted over the years and collapses like this often happen after long periods of rain, which they have had in this area.”

There’s something both uncanny and compelling about the idea that, with seasons of increased rainfall due to climate change, the nation’s mining industry might stage an unsettling reappearance, bursting open in subterranean splendor to swallow the surface world whole.

Think of it as an industrial-historical variation on the El Niño rains in Los Angeles—where huge storms were suspected of “unearthing more skeletal human remains” in the parched hills outside the city—only here given the horror movie ambience of murderous voids opening up beneath houses, making their abyssal presence felt after long winter nights of darkness and endless rain.

In any case, consider joining Subterranea Britannica for a subscription to Subterranea for more sinkhole news.

Colossal Cave Adventure

[Photo: “Mega Bike” at the Louisville Mega Cavern; photo courtesy Louisville Mega Cavern].

An underground bike park is opening up next month in a former limestone mine 100 feet beneath Louisville, Kentucky.

At 320,000-square feet, the facility is massive. Outside Magazine explains, “the park will have more than five miles of interconnected trails that range from flowing singletrack to dirt jumps to technical lines with three-foot drops. And that’s just the first of three phases to roll out this winter.”

[Photo: “Mega Bike” at the Louisville Mega Cavern; photo courtesy Louisville Mega Cavern].

That’s from an interview that Outside just posted with the park’s designer, Joe Prisel, discussing things like the challenges of the dirt they’ve had to use during the construction process and the machines they used to sculpt it.

[Photo: “Mega Bike” at the Louisville Mega Cavern; photo courtesy Louisville Mega Cavern].

It’s not the most architecturally-relevant interview, if I’m being honest, so there’s not much to quote here from it, but the very idea of a BMX super-track 10 stories underground in a limestone mine sounds like a project straight out of an architecture student’s summer sketchbook, and it’s cool to see something like this become real.

Military Cave Logistics

[Image: “Humvees are stored inside the Frigaard Cave in central Norway. The cave is one of six caves that are part of the Marine Corps Prepositioning Program-Norway, which supports the equipping of Marine Expeditionary Brigade consisting of 15,000 Marines and with supplies for up to 30 days.” U.S. Marine Corps photo by Lance Cpl. Marcin Platek].

Norwegian caves are being stuffed full of U.S. military equipment, including armored Humvees, tanks, and cargo containers full of weaponry, all part of a vast and semi-subterranean supply chain maintained to help wage future wars around the world.

The Marines have “stashed weapons and equipment in the Norwegian countryside since the 1980s,” War is Boring explains, in sites that include artificially enlarged and fortified caves. It’s all about logistics: “With this setup, Marines can fly in and be ready for a fight in no time.”

[Image: “Rows of front loaders and 7-ton trucks sit, gassed up and ready to roll in one of the many corridors in the Frigard supply cave located on the Vaernes Garrison near Trondheim, Norway. This is one of seven [see previous caption!] caves that make up the Marine Corps Prepositioning Program-Norway facility. All the caves total more than 900,000 sq. ft. of storage space, full of enough gear to outfit 13,000 Marines for up to 30 days.” U.S. Marine Corps photo by Sgt. Matt Lyman].

These facilities are commonly described as “supply caves,” and they hold warfighting gear in a state of indefinite readiness, “reserved for any time of crisis or war.”

Marines can simply fly in, unlock their respective caves, and grab the keys to one of hundreds, if not thousands, of combat-ready vehicles, all “gassed up and ready to roll in one of the many corridors” of this subterranean empire on the edges of American influence.

Among many other points of interest, the Marines identify six such supply caves in the caption of one image and seven caves in the caption of another, as if—assuming this is not just a minor clerical error—the Marines themselves don’t even know how many caves they have.

Instead, there’s just Norway, some faraway land of underground voids we’ve stuffed full of combat gear, like emperors stocking our own tombs in advance of some future demise—the actual number of caves be damned, for who will be left counting at the end of the world?

[Image: “Medium Tactical Vehicle Replacements, High Mobility Multipurpose Wheeled Vehicles and trailers, which belong to Marine Corps Prepositioning Program-Norway are staged in a storage cave at Tromsdal, Norway, Feb. 24, 2014. Marine Corps began storing equipment in several cave sites throughout Norway in the 1980s to counter the Soviets, but the gear is now reserved for any time of crisis or war.” U.S. Marine Corps photo by Lance Cpl. Sullivan Laramie].

On one level, I’m reminded of Marcus Trimble’s old joke that France has been constructing a back-up version of itself in China. It is a frenzied act of “pre-emptive preservation,” led by the cultural ministers of that sclerotic nation of well-tended chateaux who realized that la belle France could only survive if they built immediately ready copies of themselves elsewhere.

Only, in France’s case, it wasn’t willful self-burial in Norwegian caves, but in the real estate free-for-all of urban China. After all, Trimble suggested, that country’s “construction industry seems perfect for the task of backing up bricks rather than bits—cheap and powered by the brute force of sheer population. Copies of places may be made in a fraction of the time that it took to create them. If, in the event of a catastrophic episode, the part of France in question could be restored and life would go on as it was before.”

[Image: “China: ample space for a spare copy of France”; image by Marcus Trimble].

Militarize this, secret it away in a cave in Scandinavia, and you have something roughly approximately what’s called the Marine Corps Prepositioning Program.

However, I was also reminded of a recent paper by Pierre Belanger and Alexander Scott Arroyo at Harvard’s GSD. There, Belanger and Arroyo describe the U.S. military as a kind of planetary logistics challenge. (A PDF of their paper is available here courtesy of the U.S. Department of Defense).

Specifically, it is the problem of building and often violently maintaining “logistics islands,” as Belanger and Arroyo describe them, that now characterizes much of the U.S. military’s global behavior, an endless quest for finding and protecting “a secure staging ground adjacent to the theater of operations,” in an era when adjacency is increasingly hard to define. As they explain:

While logistical acquisitions are managed by the Defense Logistics Agency (DLA), logistical operations in the field are predominantly coordinated by USTRANSCOM. On average, the command oversees almost 2,000 air missions and 10,000 ground shipments per week, with 25 container ships providing active logistical support. From October 2009 through September 2010 alone, USTRANSCOM flew 37,304 airlift missions carrying over 2 million passengers and 852,141 tons of cargo; aerially refueled 13,504 aircraft with 338,856,200 pounds of fuel on 11,859 distinct sorties; and moved nearly 25 million tons of cargo in coordinated sea-land operations. DLA and USTRANSCOM and their civilian partners are responsible for the largest, most widespread, and most diverse sustained logistics operation in history.

The largest, most widespread, and most diverse sustained logistics operation in history.

The obvious and intended resonance here is that military operations perhaps now most closely resemble complicated UPS deliveries than anything like actual ground combat. However, we can also infer from this that establishing new and ever more convenient logistics islands is vital to U.S. national security.

A literal archipelago of shipping hubs is thus key to the country’s global military activities, and this not only requires sites like Diego Garcia, which Belanger and Arroyo specifically write about, or even the “mobile offshore bases” they also describe, where the pop-up urbanism of Archigram has been inadvertently realized by the U.S. military, but artificially fortified caves near the Arctic Circle where truly daunting amounts of military materiel are now kept on hand, as if held frozen in some imperial freezer, awaiting the day when global tensions truly heat up.

Read a bit more at War is Boring.

(This is more or less irrelevant, but you might also like Kiln, earlier on BLDGBLOG).

Offworld Glaciology

[Image: Photo by Gerco de Ruijter, via but does it float].

A short article by Sam Kean for the Chemical Heritage Foundation in Philadelphia explores the world of “bizarro ice—ice that burns, ice that sinks instead of floating, ice literally out of this world.” For the most part, these are ices that have formed under extraordinary pressure, whether naturally or artificially applied, which “forc[es] H2O molecules into rhombuses, tetragons, and other alternative geometries.”

In some cases, the pressure is so great that the resulting ice “can stay solid at temperatures of thousands of degrees—a true freezer burn. If you could somehow plop chunks of these ices into a glass of liquid water, they’d vaporize it.” Incredibly, we read that, “at super-high pressures, some chemists predict that ice transforms into a metal.”

There is an ice “that’s structurally similar to diamonds,” Kean explains, that “probably exists in the upper atmosphere.” And there are exotic ices on other planets: “The dense, hot interiors of Neptune and Uranus probably contain chunks of nonhexagonal ices, as do exoplanets around distant stars, a potentially important consideration as we search for life beyond our solar system.”

[Image: The Sea of Ice by Caspar David Friedrich].

This latter remark brings to mind a book I downloaded in my recent PDF binge called The Science of Solar System Ices, edited by Murthy S. Gudipati and Julie Castillo-Rogez. It’s a mammoth book—more than 650 pages—that explores exotic ices found in comets, on exoplanets, on moons, and elsewhere in our solar system.

“The largest deposits of carbon dioxide ice,” we learn, “is on Mars. Sulfur dioxide ice is found in the Jupiter system. Nitrogen and methane ices are common beyond the Uranian system. Saturn’s moon Titan probably has the most complex active chemistry involving ices, with benzene and many tentative or inferred compounds,” including a long list of chemicals I can’t even pronounce let alone recognize or describe, forming ices with “unusual colors and spectral shapes.” There are even “organic” ices made of hydrocarbons.

[Image: The Monk by the Sea by Caspar David Friedrich].

How these ices produce landscapes is by far the most interesting aspect here, at least from the point of view of BLDGBLOG: how they glaciate, experience gravitational tides and weathering, melt from below due to volcanoes, reflect the alien skies shining down on them in distorted shapes and angled echoes, and even how they tectonically fracture into karst-like networks of sinkholes and caves.

Imagining snow storms of frozen methane on other planets while thinking about, for example, human artistic traditions of landscape representation, from the Hudson Valley School to Caspar David Friedrich—picturing massive and extraordinary widescreen scenes of glacial hills and valleys steaming in the outer darkness of the solar system and the paintings or photographs or even animated GIFs that might result—would extend the idea of the sublime to non-terrestrial landscapes and the sights they might someday reveal to human explorers.

[Image: Walking into a glacier: “Grindelwald Grotto, Bernese Oberland, Switzerland,” courtesy of the Library of Congress Prints & Photographs Division].

Art historians would gaze in awe at offworld glaciers of carbon dioxide ice and howling massifs of frozen nitrogen, where volcanoes erupt not with liquid rock but with “ice slurries” and groundwater exploding onto the landscape with the force of a Kilauea.

Perhaps someday you’ll be able to get a degree in the field of exploratory xenoglaciology, the study of rare and incredible landforms made of frozen chemicals in space.

(“Wild Ice” story spotted via @nicolatwilley).

Meshworm

The last few years have seen the rise of “soft robots,” squirming, biomorphic, and highly flexible little machines that can be used to slip through cracks, infiltrate tight spaces, even explore architectural ruins in the wake of earthquakes and warfare.

But soft robots are also getting closer to becoming what are, in effect, mechanically agile medical devices that can “monitor your insides,” in the words of Sangbae Kim, assistant professor of mechanical engineering at MIT, as reprinted by Popular Science, sneaking around inside your body like an earthworm.

The so-called “meshworm” is exactly that: a robotic “worm” made from layered wire mesh that uses “nickel-titanium alloy for muscles.” The application of a high temperature “shortens the wire, tightens the spring’s coil, and squeezes that body segment.” Thus, “when a segment contracts, the one behind it stretches out, and the robot inches forward. The tendon also has muscles attached so the robot can turn left or right.”

The result is the oddly grotesque and somewhat phallic creeping machine you see in the short video, above. The idea is that this could be used for medical diagnosis or vascular surgery.

However, the architectural or broadly spatial uses of this technology are also worth considering, including the potential for monumentally scaled-up versions of the meshworm, capable of assisting human or material transport through the built environment—a kind of peristaltic package-delivery tube that could replace the much-discussed pneumatic tubes of an earlier urban era. Like something out of a David Cronenberg film, the city would have a kind of giant bowel-infrastructure distributing waste material from point to point.

More interestingly, though, this new class of soft robots and meshworms could quickly assume their roles as architectural explorers in their own right, burrowing through collapsed buildings, passing beneath or around doors, even being taken up by the more ambitious burglars and tactical operations teams of the world.

Or, for example, earlier this month in the cave state of Kentucky, the annual “Cave City Hamfest” explored how to bring radio transmission deep underground. This was “accomplished by placing handheld (relay capable) walkie-talkies or relay boxes along a cave passage.” “After the inital debugging phase, we demonstrated the ability to simply walk the cave, until data was lost and then backing up a few feet for a solid link. Then placing a radio on a convenient rock and continuing.” Taking this as our cue, we could simply wire-up a team of meshworms with radio repeaters and send a small, crawling team of spelunking robots far ahead of us into caves where no human body can fit; they would crawl until they lose a signal, move back a few feet to re-establish a secure feed, and then the next one squirms dutifully forward.

You’ve thus built a mobile, semi-autonomous, deep-earth radio network made from repurposed medical devices—equal parts cave-mapping expedition and subterranean pirate radio station—opening up whole new realms of underground exploration (and tactical media).

Caves of Nottingham

[Image: Cliffs and caves of Nottingham; photo by Nicola Twilley].

For several years now, I’ve admired from afar the ambitious laser-scanning subterranean archaeological project of the Nottingham Caves Survey.

Incredibly, there are more than 450 artificial caves excavated from the sandstone beneath the streets and buildings of Nottingham, England—including, legendarily, the old dungeon that once held Robin Hood—and not all of them are known even today, let alone mapped or studied. The city sits atop a labyrinth of human-carved spaces—some of them huge—and it will quite simply never be certain if archaeologists and historians have found them all.

[Images: Laser scans from the Nottingham Caves Survey show Castle Rock and the Mortimer’s Hole tunnel, including, in the bottom image, the Trip to Jerusalem Pub where we met archaeologist David Strange-Walker; images like this imply an exhilarating and almost psychedelic portrait of the city as invisibly connected behind the scenes by an umbilical network of caves and tunnels. Scans courtesy of the Nottingham Caves Survey].

“Even back in Saxon times, Nottingham was known for its caves,” local historian Tony Waltham writes in his helpful guide Sandstone Caves of Nottingham, “though the great majority of those which survive today were cut much more recently.” From malt kilns to pub cellars, “gentlemen’s lounges” to jails, and wells to cisterns, these caves form an almost entirely privately-owned lacework of voids beneath the city.

[Image: Map of only the known caves in Nottingham, and only in Nottingham’s city center; map by Tony Waltham, from Sandstone Caves of Nottingham].

As Waltham explains, “Nottingham has so many caves quite simply because the physical properties of the bedrock sandstone are ideal for its excavation.” The sandstone “is easily excavated with only hand tools, yet will safely stand as an unsupported arch of low profile.”

In a sense, Nottingham is the Cappadocia of the British Isles.

[Image: The extraordinary caves at 8 Castle Gate; scan courtesy of the Nottingham Caves Survey].

The purpose of the Nottingham Caves Survey, as their website explains, is “to assess the archaeological importance of Nottingham’s caves. Some are currently scheduled monuments and are of great local and national importance. Some are pub cellars and may seem less vital to the history of the City.”

Others, I was soon to learn, have been bricked off, taken apart, filled in, or forgotten.

“All caves that can be physically accessed will be surveyed with a 3D laser scanner,” the Survey adds, “producing a full measured record of the caves in three dimensions. This ‘point cloud’ of millions of individual survey points can be cut and sliced into plans and sections, ‘flown through’ in short videos, and examined in great detail on the web.”


[Video: One of very many laser-scan animations from the Nottingham Caves Survey].

While over in England a few weeks ago, I got in touch with archaeologist David Strange-Walker, the project’s manager, and arranged for a visit up to Nottingham to learn more about the project. Best of all, David very generously organized an entire day’s worth of explorations, going down into many of the city’s underground spaces in person with David himself as our guide. Joining me on the trip north from London was Nicola Twilley of Edible Geography; architect Mark Smout of Smout Allen and co-author of the fantastic Pamphlet Architecture installment, Augmented Landscapes; and Mark’s young son, Ellis.

[Image: Artificially enlarged pores in the sandstone; photo by BLDGBLOG].

We met the very likable and energetic David—who was dressed for a full day of activity, complete with a well-weathered backpack that we’d later learn contained hard hats and floodlights for each of us—outside Nottingham’s Trip to Jerusalem pub.

Rather than kicking off our visit with a pint, however, we simply walked inside to see how the pub had been partially built—that is, expanded through deliberate excavation—into the sandstone cliffside.

The building is thus more like a facade wrapped around and disguising the artificial caves behind it; walking in past the bar, for instance, you soon notice ventilation shafts and strange half-stairways, curved walls and unpredictable acoustics, as the “network of caves” that actually constitutes the pub interior begins to reveal itself.

[Image: A laser scan showing the umbilical connection of Mortimer’s Hole, courtesy of the Nottingham Caves Survey].

My mind was already somewhat blown by this, though it was just the barest indication of extraordinary spatial experiences yet to come.

[Image: Examining sandstone with Dr. David Strange-Walker; photo by BLDGBLOG].

Wasting no time, we headed back outside, where afternoon rain showers had begun to blow in, and David introduced us to the sandstone cliff itself, pointing out both natural and artificially enlarged pores pockmarking the outside.

The sandstone formations or “rock units” beneath the city, as Tony Waltham explains, “were formed as flash flood sediments in desert basins during Triassic times, about 240 million years ago, when Britain was part of a hot and dry continental interior close to the equator. Subsequent eons of plate tectonic movements have brought Britain to its present position; and during the same time, the desert sediments have been buried, compressed and cemented to form moderately strong sedimentary rocks.”

The city is thus built atop a kind of frozen Sahara, deep into which we were about to go walking.

[Image: A gate in the cliff; photo by BLDGBLOG].

Outside here in the cliff face, small openings led within to medieval tunnels and stairs—including the infamous Mortimer’s Hole—that themselves curled up to the top of the plateau; doors in the rock further up from the Trip to Jerusalem opened onto what were now private shooting ranges, of all things; and, with a laugh, David pointed out shotcrete cosmetic work that had been applied to the outer stone surface.

[Image: Artificial shotcrete geology; photo by BLDGBLOG].

We headed from there—walking a brisk pace uphill into the town center—with David casually narrating the various basements, cellars, tunnels, and other urban perforations that lay under the buildings around us, as if we were traveling through town with a human x-ray machine for whom the city was an archaeologically rich cobweb of underground loops and dead-ends.

We soon ended up at the old jails of the Galleries of Justice. A well-known tourist destination, complete with costumed re-enactors, the building sits atop several levels of artificial caves that are well worth exploring.

[Image: Scan of the Guildhall caves, courtesy of the Nottingham Caves Survey].

We were joined at this point by the site’s director, who generously took time out of his schedule to lead us down into parts of the underground complex that are not normally open to the general public.

Heading downward—at first by elevator—we eventually unlocked a door, stepped into a tiny room beneath even the jail cells, crouching over so as not to bang our heads on the low ceiling, and we leaned against banded brick pillars that had been added to help support all the architecture groaning above us.

Avoiding each other’s flashlight beams, we listened as our two guides talked about the discovery—and, sadly, the willful reburial—of caves throughout central Nottingham.

[Image: Brick pillars below Nottingham; photo by BLDGBLOG].

We learned, for instance, that, elsewhere in the city, there had once been a vacuum shop with a cave beneath it; if I remember this story correctly, the shop’s owners had the habit of simply discarding broken and unsold vacuum cleaners into the cave, inadvertently creating a kind of museum of obsolete vacuum parts. Discontinued models sat in the darkness—a void full of vacuums—as the shop went out of business.

We heard, as well, about a nearby site where caves had been discovered beneath a bank during a recent process of renovation and expansion—but, fearing discovery of anything that might slow down the bank’s architectural plans, the caves were simply walled up and left unexplored. They’re thus still down there, underneath and behind the bank, their contents unknown, their extent unmapped—a fate, it seems, shared by many of the caves of Nottingham.

Rather than being greeted by the subterranean and historical wonder that such structures deserve—and I would argue that essentially all of subterranean Nottingham should be declared a UNESCO World Heritage Site—the caves are too often treated as little more than annoying construction setbacks or anomalous ground conditions, suitable only for bricking up, filling with concrete, or forgetting. If the public thinks about them at all, in seems, it is only long enough to consider them threats to building safety or negative influences on property value.

[Images: Learning about caves; photos by BLDGBLOG].

In any case, on our way out of the Galleries of Justice, we lifted up a ventilation grill in the floor and looked down into a small vertical shaft, too narrow and contorted even for Ellis to navigate, and we learned that there are urban legends that this particular shaft leads down to a larger room in which Robin Hood himself was once held… But we had only enough time to shine our flashlights down and wonder.

[Images: Ellis Smout looks for Robin Hood below; photos by BLDGBLOG].

From here, we headed over to our final tourist-y site of the day, which is the awesomely surreal City of Caves exhibition, located in Nottingham’s Broad Marsh shopping mall.

You literally take an escalator down into an indoor mall, where, amidst clothing outlets and food courts, there is an otherwise totally mundane sign pointing simply to “Caves.”

If you didn’t know about Nottingham’s extensive sub-city, this would surely be one of the most inexplicable way-finding messages in mall history.

[Image: Caves; photo by Nicola Twilley].

Here, where we picked our copy of Tony Waltham’s Sandstone Caves of Nottingham pamphlet, from which I’ve been quoting, we learned quite a bit more about how the city has grown, how the caves themselves have often been uncovered (for example, during building expansions and renovations), and what role Nottingham’s underground spaces served during the Nazi bombings of WWII.

[Image: Beneath Broad Marsh shopping mall; photo by BLDGBLOG].

The specific underground complex beneath the shopping mall offers an interesting mix of old tanning operations and other semi-industrial, pre-modern work rooms, now overlapping with 20th-century living and basement spaces that were sliced open during the construction of the Broad Marsh mall.

[Images: Cave spaces beneath the Superstudio-like concrete grid of Nottingham’s Broad Marsh shopping Mall].

That these caves were preserved at all is testament to the power of local conservationists, as the historically rich and spatially intricate rooms and corridors would have been gutted and erased entirely during post-War reconstruction without their intervention.

As it now stands, the mall is perched above the caves on concrete pillars, with the effect that curious shoppers can wander down into the caves through an entrance that could just as easily lead to a local branch of Accessorize.

[Image: A well bucket in the caves beneath Broad Marsh; photo by BLDGBLOG].

Again, we were fortunate to be taken down into some off-limits areas, stepping over lights and electric wires and peering ahead into larger rooms not on the tourist route.

[Images: Lines of lights we switched on in one of the off-limits rooms below Broad Marsh; photo by BLDGBLOG].

This included stepping outside at one point to wander through an overgrown alleyway behind the mall. Small openings even back here stretched beneath and seemingly into the backs of shops; one doorway, a short scramble up a hill of weed-covered rubble, appeared to contain a half-collapsed spiral staircase installed inside a brick-lined sandstone opening.

[Image: A doorway to voids behind Broad Marsh Centre; photo by BLDGBLOG].

At this point, we began to joke about the ease with which it seemed you could plan a sort of speleological super-heist, breaking into shops from below, as an entire dimension of the city seemed to lie unwatched and unprotected.

Nottingham, it appeared, is a city of nothing but doors and openings, holes, pores, and connections, complexly layered knots of space coiling beneath one building after another, sometimes cutting all the way down to the water table.

Incredibly, the day only continued to build in interest, reaching near-impossible urban sights, from catacombs in the local graveyard to a mind-bending sand mine that whirled and looped around like smoke rings beneath an otherwise quiet residential neighborhood.

Leaving the mall behind, and maintaining a brisk pace, David took us further into the city, where our next stop was the Old Angel Inn, another pub with an extensive cellar of caves, in this case accessed through a deceptively workaday door next to an arcade game.

[Images: The Old Angel Inn (top), including the door inside the pub that leads down to the caves below; photos by Nicola Twilley].

Once again, it can hardly be exaggerated how easy it would be to visit or even live in Nottingham and have absolutely no idea that underground spaces such as this can be found almost anywhere. As Tony Waltham points out, “It would be a fair assumption that every building or site within the old city limits either has or had some form of cave beneath it. About 500 caves are now known, and this may be only half the total number that have been excavated under Nottingham.”

[Images: The caves of the Old Angel Inn, courtesy of the Nottingham Caves Survey].

In any case, “Although the Old Angel is a ‘modern’ brick building,” as the Nottingham Caves Survey describes the pub on its website, “an investigation of the caves below reveals stone walls belonging to an earlier incarnation. It is likely that there were buildings on this site as far back as the Anglo-Saxon period. Whether the caves beneath are also this old cannot be demonstrated definitively.”

Typical, as well, for these types of pub caves, we found ventilation and delivery tunnels leading back up to the surface, and the walls themselves are lined with long benches, perfect for sitting below ground and, provided you have candles or a flashlight along with you, enjoying a smoke and a pint of beer. As Tony Waltham explains, pub cellars often include “perimeter thralls,” or “low ledges cut in the rock,” normally used for storing kegs and barrels of beer but quite easily repurposed for a quick sit-down.

But I sense I’m going on way too long about all this, especially because the two most memorable details of the entire day were yet to come.

Jumping forward a bit, we left the Old Angel and followed some twists and turns in the street to find ourselves standing outside a nightclub called Propaganda.

Here, David revealed that he has been working on what, in my opinion, will easily be one of the must-have apps of the year. In a nutshell, David has managed to make the subterranean 3D laser-scans of the Nottingham Caves Survey accessible by location, such that, holding up his iPod Touch, he demonstrated that you could, in effect, scan the courtyard we were standing in to see the caves, tunnels, stairways, cellars, vents, storage rooms, and more that lay hidden in the ground around us.

[Images: We test-drive the cave-spotting app; bottom photo by Nicola Twilley].

Ideally, once the Survey’s extensive catalog of 3D visualizations and laser point-clouds has been made available and the app is ready for public download, you will be able to walk through the city of Nottingham, smartphone in hand, revealing in all of their serpentine complexity the underground spaces of the city core.

For anyone who has ever dreamt of putting on x-ray glasses and using them to explore architectural space, this app promises to be a thrilling and vertiginous way to experience exactly that—peering right through the city to see its most ancient foundations.


[Video: A fly-through of the Propaganda Nightclub malting caves].

I, for one, can’t wait to see what David and the Nottingham Caves Survey do with the finished application and I eagerly await its public availability.

[Image: Mark Smout looks for caves in the sky; photo by Nicola Twilley].

I’ll wind up this already quite long post with just a few more highlights.

Nottingham’s Rock Cemetery, north from the center of town along the Mansfield Road, contains, among other things, the collapsed remains of a sand mine. Three of the mine’s old entrances are now gated alcoves surrounded by graves, like something out of Dante. They “are the only surviving remnants of the mine,” Waltham writes in his pamphlet.

[Images: Nottingham’s Rock Cemetery, where archaeologist David Strange-Walker explained the history of the local landscape].

However, an ambitious plan to carve sizable catacombs, inspired by Paris and Rome, through the sandstone beds of the ancient desert here resulted in the never-completed Catacomb Caves, “probably done in 1859-63,” Waltham suggests. These long arched tunnels, accessible through one of the gates described above, eventually lead to a radial terminus from which branch the unused proto-catacombs.

The air there is cloudy with sand—leading me, several days later, to experience a brief attack of hypochondria, worried about developing silicosis—the walls are graffiti’d, and years of trash are piled on the sides of the sandy floor (which has since taken on the characteristics of a dune sea in places, as 150 years of footfall and a collapsing ceiling have led to the appearance of drifts).

[Images: The Rock Cemetery catacomb gates].

What was so extraordinary here, among many other things, was that, for most of this walk through the catacombs, we were actually walking below the graves, meaning that people were buried above us in the earth. At the risk of overdoing it, this felt not unlike becoming aware of an altogether different type of constellation, with bodies and all the stories their lives could tell held above us in a terrestrial sky like legends and heroes, like Orion and Cassiopeia, as we looked up at the vaulted ceiling, flashlights in hand.

[Image: Inside the catacombs; photo by Nicola Twilley].

But the best site of all was next.

[Image: A door on the street—the black door with bars—leading down into a sand mine; photo by BLDGBLOG].

Serving as something of the ultimate proof that Nottingham is a city of overlooked doors that lead into the underworld, there were two locked doors—one of which (the black door, near the sidewalk) appears in the photo, above, another of which, on a street nearby, leads down into the Peel Street Caves—simply sitting there on the sidewalk that, if opened, will take you down into extensive and now defunct sand mines. David’s laser-scans of these for the Nottingham Caves Survey are absolutely gorgeous, as you can see, below.

[Image: The Peel Street Caves sand mine, courtesy of the Nottingham Caves Survey].

For a variety of reasons, I am going to avoid being too specific about some of the details here, but, aside from that, I can only enthuse about the experience of donning our hard hats and heading down several flights of comparatively new concrete steps into a coiling and vast artificial cavern from the 19th century, one we spent nearly an hour exploring.

[Image: Nicola Twilley and Mark Smout head down into the sand mine; photo by BLDGBLOG].

Getting lost down there would be so absurdly easy that it is frightening even to contemplate, and, in case the group of us somehow got split up or our batteries ran out of juice, we joked about—if only we could remember them—the easy techniques for navigating a labyrinth offered in Umberto Eco’s novel The Name of the Rose.

[Image: Many of these way-finding signs are actually incorrect, David explained, and seem to have been painted as a kind of sick joke by someone several years ago; photos by BLDGBLOG].

Avoiding such a fate, however, we found graffiti and men’s and women’s latrines; we popped our heads through holes allowing glimpse of other levels; and we cracked our helmets loudly against the low and rough roof more times than I could count.

[Images: Inside the sand mine; all photos by Nicola Twilley].

And even that doesn’t complete the day. From here, heading back out onto the street through a nondescript steel door, as if we had been doing nothing more than watching football in someone’s basement, we went on to eat pie and chips in a restaurant built partially into a cave; we walked back across town, returning to where we started, talking about the future and seemingly obvious possibility of Nottingham’s caves being declared a UNESCO World Heritage Site and thus saved from their all but inevitable destruction (it’s easy to imagine a future in which a tour like the one David gave us will be impossible for lack of caves to see); and we all said goodbye beneath an evening sky cleared of clouds as a late-day breeze began to cut through town.

[Image: Mark & Ellis Smout explore our final “underground” space of the day, the magnificent Park Tunnel; the banded strata clearly visible in the walls show how the tunnel was carved through the dunes of an ancient desert. Photo by BLDGBLOG].

David proved to be a heroic guide that day. His energy never flagged throughout the tour, and he never once appeared impatient with or exhausted by any of our often ridiculous questions—not to mention our tourists’ insistence on pausing every three or four steps to take photographs—and he remained always willing to stay underground far longer than he had originally planned, all this despite having never met any of us before in person and only communicating with me briefly via a flurry of emails the week before.

Meeting David left me far more convinced than I already was that the Nottingham Caves Survey fully deserves the financial support of individuals and institutions, so that it can complete its ambitious and historically valuable work of cataloging Nottingham’s underground spaces and making that knowledge freely accessible to the general public.

Weirdly, England has within its very heart a region deserving comparison to Turkish Cappadocia—yet very few people even seem to know that this subterranean world exists. There very well could be more than 1,000 artificial caves beneath the city, many of them fantastically elaborate, complete with fine carvings of lions and ornate stairwells, and it is actually somewhat disconcerting to think that people remain so globally unaware of Nottingham’s underground heritage.

With any luck, the work of David Strange-Walker, Trent & Peak Archaeology, and the Nottingham Caves Survey will help bring this extraordinary region of the earth the attention—and, importantly, the focused conservation—it is due.

(For further reading, don’t miss Nicola Twilley’s write-up of the tour on her own blog, Edible Geography; and Tony Waltham’s Sandstone Caves of Nottingham, cited extensively in this post, is worth a read if you can find a copy).

Speleological Superparks

[Image: Downtown Reno on a Saturday night with people queuing up to climb the BaseCamp wall; photo by BLDGBLOG].

As part of an overall strategy to rebrand itself not as a city of gambling and slot machines—not another Las Vegas—but as more of a gateway to outdoor sports and adventure tourism—a kind of second Boulder or new Moab—Reno, Nevada, now houses the world’s largest climbing wall, called BaseCamp, attached to the side of an old hotel.

[Image: The wall; photo by BLDGBLOG].

BaseCamp is “a 164-foot climbing wall, 40 feet taller than the previous world’s highest in the Netherlands,” according to DPM Climbing. “The bouldering area will also be world-class with 2900 square feet of overhanging bouldering surface.”

You can see a few pictures of those artificial boulders over at DPM.

[Image: The wall; photo by BLDGBLOG].

Fascinatingly, though, the same company who designed and manufactured this installation—a firm called Entre Prises—also makes artificial caves.

One such cave, in particular, created for and donated to the British Caving Association, is currently being used “to promote caving at shows and events around the country. It is now housed in its own convenient trailer and is available for use by Member Clubs and organizations.”

[Image: The British Caving Association’s artificial cave, designed by Entre Prises; photo by David Cooke].

These replicant geological forms are modular, easily assembled, and come in indoor and outdoor varieties. Indoor artificial caves, we read, “are usually made from polyester resin and glass fibre as spraying concrete indoors is often not very practicable. Indoor caves provide the experience of caving without some of the discomforts of natural or outdoor caves: the air temperature can be relatively easily controlled, in most cases specialist clothing is not required [and] the passage walls are not very thick so more cave passage can be designed to go into a small area.”

Further, maintaining the exclamation point from the original text: “The modular nature of the Speleo System makes it possible to create any cave type and can be modified in minutes by simply unbolting and rotating a section! This means you can have hundreds of possible caving challenges and configurations for the price of one.”

It would be interesting to live in a city, at least for a few weeks, ruled by an insane urban zoning board who require all new buildings—both residential and commercial—to include elaborate artificial caves. Not elevator shafts or emergency fire exits or public playgrounds: huge fake caves torquing around and coiling through the metropolis. Caves that can be joined across property lines; caves that snake underneath and around buildings; caves that arch across corporate business lobbies in fern-like sprays of connected chambers. Plug-in caves that tour the city in the back of delivery trucks, waiting to be bolted onto existing networks elsewhere. From Instant City to Instant Cave. Elevator-car caves that arrive on your floor when you need them. Caves on hovercrafts and helicopters, detached from the very earth they attempt to represent.

This brings to mind the work of Carsten Höller, implying a project someday in which the Turbine Hall in London’s Tate Modern could be transformed into the world’s largest artificial cave system, or perhaps even a future speleo-superpark in a place like Dubai, where literally acres of tunnels sprawl across the landscape, inside and outside, aboveground and below ground, in unpredictably claustrophobic rearrangeable prefab whorls.

The “outdoor” varieties, meanwhile, are actually able “to be buried within a hillside”; however, they “must be able to withstand the bearing pressure of any overlying material, eg. soil or snow. This is usually addressed by making the caving structures in sprayed concrete that has been specifically engineered to withstand the loads. Alternatively the cave passages can be constructed in polyester resin and glass fibre but then they have to be within a structural ‘box’ if soil pressure is to be applied.”

In any case, here are some of the cave modules offered by Entre Prises, a kind of cave catalog called the Speleo System—though it’s worth noting, as well, that “To add interest within passages and chambers, cave paintings and fossils can be added. This allows for user interest to be maintained, creating an educational experience.”

[Image: The Speleo System by Entre Prises].

As it happens, Entre Prises is also in the field of ice architecture. That is, they design and build large, artificially maintained ice-climbing walls.

These “artificial ice climbing structures… support natural ice where the air temperature is below freezing point.” However, “permanent indoor structures,” given “a temperature controlled environment,” can also be created. These are described as “self generating real ice structures that utilize a liquid nitrogen refrigeration system.”

[Images: An artificial ice structure by Entre Prises for the Winter X Games].

Amongst many things, what interests me here is the idea that niche sports enthusiasts—specifically cavers and climbers—have discovered and, perhaps more importantly, financially support a unique type of architecture and the construction techniques required for assembling it that, in an everyday urban context, would appear quite eccentric, if not even avant-garde.

Replicant geological formations in the form of modular, aboveground caves and artificially frozen concrete towers only make architectural and financial sense when coupled with the needs of particular recreational activities. These recreational activities are more like spatial incubators, both inspiring and demanding new, historically unexpected architectural forms.

So we might say that, while architects are busy trying to reimagine traditional building typologies and architectural programs—such as the Library, the Opera House, the Airport, the Private House—these sorts of formally original, though sometimes aesthetically kitsch, designs that we are examining here come not from an architecture firm at all, or from a particular school or department, but from a recreational sports firm pioneering brand new spatial environments.

As such, it would be fascinating to see Entre Prises lead a one-off design studio somewhere, making artificial caves a respectable design typology for students to admit they’re interested in, while simultaneously pushing sports designers to see their work in more architectural terms and prodding architects to see niche athletes as something of an overlooked future clientele.

A Visitors Center for the Center of the Earth

I received a strange packet in the mail last week, full of maps and images hand-annotated with ball-point pen and partly held together with red duct tape. It implies—more than it describes—a subterranean expedition in a boat led by an unnamed explorer (“note,” it says, “expedition almost goes down the drain,” with an arrow pointing into the abyss).

[Images: Two illustrations for Dante’s Inferno, both by Gustav Doré].

The actual purpose of the elaborate packaging, however, was to announce that there is a party and “underground fundraiser” in Austin, Texas, from 6-8pm on Thursday night of this week, celebrating the opening of a (fictitious) “center of the earth visitors center” and benefiting an organization called the Austin Bat Cave, “a nonprofit writing and tutoring center for kids.” If you’re in the area and interested in attending, contact underground(at)austinbatcave(dot)org, and tell them that you read about it on BLDGBLOG.

[Image: Viewmaster images of the Center of the Earth Visitors Center by Legge Lewis Legge architects].

As architects Legge Lewis Legge describe their plans for this fictitious complex in Austin, it will be “a visitors’ center for a cave system recently rediscovered underneath the City of Austin, Texas.”

The labyrinthine system of caves and tunnels is only partially explored. The cave system’s first explorers noted many years ago that “some cave passageways have been observed to lead toward the very center of the earth.” Along with Austin Bat Cave, Legge Lewis Legge are concepting and designing the Center, as well as assisting with mapping and rendering cave and tunnel interiors from descriptions recorded long ago when the caves were first discovered.

The idea of a visitors center for the center of the earth is pretty fantastic design brief; I would love to see this taken up as the broader premise of an architectural challenge or summer workshop. In other words, what facility for preparing surface visitors for their forthcoming visit to the center of the earth would be most appropriate (and fun) to design? A museum of the earth’s core; a series of hands-on, experiential pressure chambers; a make-your-own-stalactites class; a mind-bogglingly elaborate series of wormhole-like passages that you crawl and squeeze your way through, for hours at a time, in preparation for the abyss that awaits you.

[Image: The Jenolan Caves in Australia; photo by BLDGBLOG].

Perhaps a worthwhile reference for any such class would be Jeff Long’s over-the-top but undeniably enjoyable, religiously-inflected science-horror novel The Descent, published back in 2001, for its proposed architectural exploration of the planet’s interior—suggesting that liberal applications of hydroponic agriculture, UV lights, and seemingly endless quantities of instant concrete could allow for an organized human “descent” into the planet.

Long writes that his underworld explorers “approached the subplanet the way America [sic] approached manned landings on the moon forty years ago, as a mission requiring life support systems, modes of transportation and access, and logistics.” Accordingly, the Army Corps of Engineers gets involved, “tasked to reinforce tunnels, devise new transport systems, drill shafts, build elevators, bore channels, and erect whole camps underground. They even paved parking lots—three thousand feet beneath the surface. Roadways were constructed through the mouths of caves.”

Apply the personal infrastructure of caving on an industrial scale; devise a visitors center for people about to embark upon an exploration of that underground world; produce a Center of the Earth reading & viewing list for the interested public; and use the whole thing as an excuse to talk about the uniquely challenging design constraints of architecture in extreme environments. The best project wins a lifetime membership at Mammoth Cave.

[Image: The way out. Jenolan Caves, Australia; photo by BLDGBLOG].

In any case, if you’re in the vicinity of Austin, Texas, consider contacting the email address, above, to find out more about the fundraiser.