GregBrick.org

GLOSSARY OF URBAN CAVE TERMS

First Edition

(5/1/2010)

Copyright 2010 by Greg Brick

Alpine Illusion.A weird thing about the Davern Street tunnel in St. Paul was the so-called Alpine illusion. As I walked through this tunnel, I passed under shafts with manhole lids at wildly varying heights above me, as if one manhole was situated on a peak, another in a valley. I conjectured that the higher lids represented the true street level, far above, while I inferred, from the lower lids, a set of passages above the one I was in, which later proved to be the case. (STC)

Altars.Any shelf-like votive niche carved in sandrock caves, and presumed to be related to devil worship. Yah, I bet.

Amphipods.Also known as scuds, or freshwater shrimp, they are famously a food of trout, and thus indicative of good water quality. Even so, they are sometimes abundant in storm drains, as under the city of Red Wing, MN.

Anthropogenic Caves.Neither natural nor man-made, in a strict sense; they are an inadvertent result of human activities. The classic example is Schieks Cave, a sewer washout that got going after the carving of the North Minneapolis Tunnel, beginning in 1889. (STC)

Arthur Gordon Pym.Hero of Poes novel of the same name. Some of the weird things seen in sewers remind me of that book.

Bats in the sewers.Years ago, Professor Goehring, of St Cloud State University, made a special study of bats that hibernated in chinks in the sewers of that Minnesota city. I recall entering some of those granite-block sewers myself, and until they were repointed in recent years, they afforded a nice resting place for certain species. Another place I recall seeing bats in abundance was the Bassett Creek Tunnel in Minneapolis, especially near the outfall.

Beavers.There are a few cases in the literature of beavers inhabiting caves, such as the beavers observed in Huntsville, Alabama, caves by the NSS librarian, Bill Torode, in the early 1970s. But its certainly rare. And those were limestone caves.

Along with friends, I once went exploring an abandoned sandrock sewer in St. Paul, just upriver from the Lake Street Bridge. The old hand-carved tunnel, which probably dated to the early twentieth century, was of standing height, and filled waist-deep with painfully cold groundwater seepage. Talus at the foot of the river bluff dammed the water back. The passage went straight into the bluff for a hundred feet or so before turning to the left, where it ended within 20 feet. I was the last to enter, and shortly after there was a commotion in the darkness ahead of me. Seems a beaver was trying to get outtrying to get past us underwater in the narrow tunnel! The water was murky from all the silt we had stirred up, so I couldnt see him coming, adding to the suspense. A moment later, I felt a beaver go bump against my thighs on his way out. Hardly had we got over this, when a second beaver came down the pike, also bumping me underwater. Turning toward the entrance, we watched them exit the cave. With Mr. & Mrs. Beaver gone, one of the guys went on to examine the odorous nest of sticks, perched on a sandstone ledge just above water level at the very end of the tunnel, beyond the elbow. I went home cracking bad beaver jokes for several days, to the annoyance of everyone within earshot.

It wasnt my first experience with cave-dwelling beavers, however. In 1999, I entered Carvers Cave, a natural sandstone cave, also located in St. Paul, when a beaver slapped his tail repeatedly on the waters of the subterranean lake as he circled about, impatient for me to vacate the premises. The beaver had stowed a cache of willow twigs on the beach just inside the steel doors, and it remained there for months afterwards, though I never encountered him again.

Bell & Spigot.Terra cotta pipe segments placed end to end and used for drainage. They have an ancient lineage, according to Garrisons History of Drainage (1929): the jointed cannon-shaped terra cotta sewer-pipes of the Cretan palaces at Knossos (3500 BC) and Tiryns (1450-1250 BC). Later, applied to a sewer comic strip authored by yours truly, and published in the MSS newsletter in the 1980s.

Biofilm.Some of the earliest body fossils known to geologists are biofilms: the blue-green algae of the Precambrian stromatolites. Today, biofilms, or microbial mats, are known from chemautotrophic caves, like Movile Cave in Romania. Here, however, I will mention only the sewer slimes, which constitute genuine biofilms; and where biofilms have a goodly supply of nutrients, as in tunnels draining breweries, you can find them in the form of pendant (hanging) slimes. See Snottites.

Black Spot.A fungal disease of wet clothing, when tightly packed away, associated with a powerful ammoniacal odor. (STC)

Blood Sewers.I found this delightful term used by Hollingshead with regard to the Victorian sewers draining from slaughter houses. In one case, a beef heart had clogged the drain. Now I would imagine it would all flow into a sanitary sewer. The rats in the blood sewers were especially bad.

Brain Coral.Microgoured flowstone in rounded masses, best seen in the some of the former side-passages of the old Davern Street tunnel, before it was relined in 1993. (STC)

Cave Food Pyramids.In the old days, ecologists frequently depicted trophic relationships in terms of a pyramidal diagram, but since then ecologists think more in terms of food webs. The most complex is that of Schieks Cave, with its multiple trophic levels.

Cave Unit.One particular layer within the St. Peter, called the Cave Unit by Professor Robert Sloan, is more susceptible to piping, and thus more favorable to cave formation, than the others. (STC)

Champagne-&-Oysters.In my days as an environmental consultant, I was present at various excavations about the city. Usually you just saw fairly boring soil, but occasionally more interesting things were uncovered. One time, we hove into old fill material in Minneapolis that was studded with discarded champagne bottles and oyster shells. Stratigraphic evidence, I suppose, of former good times?

Cheese Ripening in Caves.Humans have been using caves to ripen cheese for millennia. The story of the Cyclops cave, where an early type of the popular Greek Feta was ripened, appears in Homers Odyssey. The French Roquefort caves have a history dating back to Classical Antiquity. In the first century A.D., the Roman scholar Pliny the Elder was said to have served this cheese to guests in his villa outside Rome. The blue, aristocratic veins running through the cheese were partly responsible for Roquefort being called Le Roi des Fromagesthe King of Cheeses. Italys Gorgonzola and Englands Stilton are similar, blue-veined cheeses.

Professor Willes Barnes Combs, a native of Missouri, was appointed Professor of Dairy Industry at the University of Minnesota in 1925. He soon discovered a queer local fact. There are dozens of sandstone caves in St. Paul. In the late 1920s, while shopping for mushrooms at a cave in St. Paul, the grower informed him that the atmosphere of the caves was extremely moist. Combs conjectured that the caves might have a combination of temperature and humidity similar to the celebrated Roquefort caves of France, where Roquefort cheese is ripened.

Prof. Combs now has found that Roquefort conditions are approximated by the sandstone caves along the Mississippi in the Twin Cities area, a newspaper reported. St. Pauls caves, according to Combs, were the only caves in this country where temperature and humidity are similar to those in France. Artificial ripening chambers, or mechanical caves, had been tried in the past, but they proved so costly to build and operate that they had not attained success on a commercial scale. We cant set up a room like this, Combs explained. A crucial problem was to hold the temperature low while maintaining high humidityan almost paradoxical combination.

Million Yearly Cheese Trade Seen Here, crowed the St. Paul Pioneer Press, on January 6, 1935, reporting how the dairy chief, Combs, disclosed that nearly 10,000 pounds of Roquefort-type cheese, the flavor of which amazed epicures, was cured this year in a small, experimental cave, within a few minutes walking distance from St. Pauls City Hall. Popular Science magazine featured the University cave in its April, 1935, issue under the heading, Caves for Cheese Making Discovered in America. Combs claimed that there were enough caves near St. Paul to supply the entire world demand for Roquefort.

Having begun with such fanfare, Combs Roquefort project unexpectedly dropped out of sight for awhile. The fall of France to invading German armies in June, 1940, however, cut off French imports decisively. Citys Million-Dollar Cheese Industry Gets Off With Bang, trumpeted the Pioneer Press on December 15, 1940. In the autumn of 1940, the Kraft Cheese Company of Chicago rented one big cave, 150 feet deep from Villaume and its K-men began marketing the ROKA brand of blue cheese, while the Land OLakes Company, its rival just down the bluff, rented two caves, 100 feet deep, at the former Castle Royal nightclub, which had gone bankrupt in 1940. In January 1941, the first commercial blue cheese from St. Pauls caves hit the market. One reporter declared that St. Paul is well on its way to become the blue cheese capital of the world. (STC)

China Door.The deepest doors in the 3D utility labyrinths. Because you might pop out on the other side of the world?

Claustrophobia.Fear of tight places, apparently. I have more of a tendency to succumb to this ailment while flying coach, than underground.

Cloaca Maxima.Large sewer outfalls, like the one that Tarquin built (many years BC) to drain the groundwater of the Roman Forum wetland, but later used for human sewage. Now applied generically to the main drain of any town.

Cloacina.The spirit of the Great Drain, according to a history of the Roman Forum.

Cockroaches.The most notorious example of a local cave swarming with roaches, like the cockroach caves of the tropics, was Schieks Cave, which during the 1970s and 80s blackened the vaults. After that, they went away, and never recolonized the cave.

Coke-bottle Weathering.Characteristic of unlined manholes: the narrow neck was drilled in the hard Platteville Limestone, while the wide bottom in the softer, more easily eroded St Peter Sandstone. Seen especially in the Fort Road Labyrinth.

Coliform Aerosols.See Rinkers Revenge.

Death in Caves.St. Pauls Mushroom Valley has earned a bad reputation in recent decades for the injuries and fatalities that have occurred there. But cave accidents are made conspicuous by their very rarity. Unfortunately, some of the things that were done to the caves years ago have made them less safe than they were before. On the other side, some would like to blame the caves for their misfortunes instead of taking personal responsibility. So everyone has a role to play in preventing further tragedies.

The incidents in St Paul occurred after the caves were left vacant, no longer utilized. Broadly speaking, there are two different groups of caves where the incidents occurred, each having a different problem. Along Water Street, where most of the caves are empty, the problem is ceiling collapse, usually caused by campfires and/or loud music, whereas along Plato Boulevard, where most of the caves are filled with flammable wood, the problem is usually carbon monoxide poisoning. I will give a few examples of each.

As early as 1954, a landslide killed Eddie Brown, a 3-year old boy, during a visit to the abandoned Mystic Caverns, at the west end of Water Street. Death ended a day of funa 60-pound chunk of sandstone fell from above the cave archand struck him on the head. Mrs. Brown, who became hysterical, was put under sedatives at the hospital. We learn from a follow-up that Mystic Caverns was the scene of wild parties by teenagers in the 1950s. Then as now, no one could figure out how to seal a cave properly. It had been boarded up, even blocked off with cement blocks, and still had been broken into, the report said. Police had suggested the cave be dynamited to destroy it.

An increasing number of caves became vacant along Water Street in the late 1970s, especially after Ramsey County bought out the old Altendorfer and Biscliglia mushroom farms. Water Street formed a connection between the Harriet Island and Lilydale segments of a proposed regional park. The first incident occurred on May 26, 1984, when Cave No. 532 (a designation based on its Water Street address) collapsed, killing one person from skull fracture and paralyzing another with a broken spine. A campfire, lighted to provide warmth in the chilly cave, had dried and weakened the sandstone ceiling. In response, city officials smashed in the roof of the cave, a solution that was effective in this case because the cave was on a slope and there were no buildings above it. On October 20, 1993, two teenagers were critically injured in another cave collapse along Water Street.

In 1985, the old High Bridge was demolished, and the resulting concrete chunks were shoved into the abandoned caves along Water Street. This was the origin of the bizarre rebar snakepits in the caves, with the twisted steel rods projecting outwards in all directions. I could tell what cave I was inBig Snake or Little Snakefrom what diameter rebar it contained, one inch or one half inch, respectively. This was another unsuccessful exercise in filling caves, but at least here, the fill material was noncombustible.

On Plato Boulevard it was a different story. In 1969, as part of the St. Paul Housing and Redevelopment Authoritys Riverview Industrial Project, which began in the wake of the 1965 flood, numerous old structures on the floodplain were razed and the debris was bulldozed into the vacant caves along Plato Boulevard, forming the cursed wood fill that plagues us to this day. These caves are so dry and dusty that its easy to see how a rip-roaring fire could get going. The wood was repeatedly set on fire by trespassers in the caves, where it smoldered, causing carbon monoxide poisoning, sometimes long after flames were no longer visible, and the air appeared clear. Although passersby sometimes reported smoke billowing from cave entrances, firefighters do not usually go into the caves to extinguish these fires owing to the risks involved.

The Peltier Caves, on Plato Boulevard, became notorious after the death of two 17 year-old girls there on September 26, 1992, overcome by carbon monoxide in a low spot in the cave from past fires. City officials initially sealed the caves with bobcats. A warning sign was erected outside the cave by the parents, reminding potential explorers about the fate of the two girls, but a dozen years later, on April 27, 2004, three more teenagers, each 17 years old, walked right past that very sign and died in neighboring Fandells Cave, also from carbon monoxide poisoning. To be sure, the more mundane day-to-day occupational hazard in these caves is not asphyxiation, but tetanus, from the ever shifting, nail-studded cave fill. (STC)

Detritus Ecosystem.Organisms that live by ingesting POM (particulate organic matter)also known as junk foodsuch as the Carvers Cave amphipods, which live off the leaf litter that blows into the cave entrance.

Dr. Suesss Tunnels.The multigenerational sandrock tunnels dug by multiple utilities, leading to very unusual spaces. (STC)

Dropshaft Frogs.In 1953, Dr. Barr published an article in which he marveled at how frogs could survive an 80-foot drop into a natural cave in New York. I got the same feeling myself upon finding frogs that had survived the fall down the Loring dropshaft into the Geysir Drain, about an equal fall. (STC)

Dropshaft Pearls.Like cave pearls, these ovoid masses of mineral matter are formed by rotating in the impact of water drops, thus getting an even coating of calcite.

Dungeons & Dragons caves.Where you find the implements, as formerly at the Heinrich Brewery cave in Minneapolis. (STC)

Earthworms.By their very name they're worms of the earth, and thus likely to be found in caves, as indeed they are, most notably in Schieks Cave, where they cover parts of the floor "like spaghetti."

Eels.They sometimes ascend the storm drains, and can even be found in water-mains. I once met some ghostly pale eels in the brownstone labyrinth below Hartford, CT, which had ascended the Connecticut River from Long Island Sound.

Egyptian architecture.Ive noticed over the years a vaguely Egyptian motif in much sewer architecture, the best example being the Schieks Cave pyramids. (STC)

Eutrophic.Literally, well fed; adjective applied to water-bodies or caves surcharged with nutrients. The prime example of an eutrophic cave is Schieks Cave, containing, as it did for many years, the infamous Black Sea, a result of sewer leakage.

Felsenkellers.Literally, rock cellars, what the German immigrants to St. Paul built from the 1940s onwards. Compare the word feldspar (one of the most common minerals in the Earths crust) to get the word root.

Flowstone.A mineral coating deposited by flowing water.

Fly & Worm Association.Characteristic of caves heavily polluted with sewage, such as Schieks Cave.

Fungi Imperfecti.The common white mycelial threads seen growing on scats everywhere in the tunnels. Not to be confused with the wood-rotting fungi that feature in the Velvet Underground chapter of my book.

Gargoyles.When wall-mounted water spouts in old tunnels become encrusted with minerals, they can take on a shape their creators never imagined.

Gegenschein.The ghostly reflection of flashlight beams from water surfaces onto sewer walls, producing the momentary illusion that someone was approaching or receding from me in the tunnels. Borrowing a term from astronomy, I referred to this reflectance by the German word, Gegenschein, meaning counter glow. Pretty soon, you begin to hear voices in the dripping water, too. (STC)

Ghosts.Ghosts are said to infest Castle Royal, the subterranean nightclub in St. Paul, and they were featured in a 1982 TV production. But theres a more prosaic explanation, based on my past experience in the caves of Mushroom Valley. Years ago, I recall exploring a nearby cave when I heard girls chatting and giggling somewhere in the darkness ahead of me. When they heard me, however, they must have clammed up, fearing the consequences of meeting a stranger in such vulnerable circumstances. Likewise, Im wondering how many of the poltergeists in Castle Royal were actually explorers who came in through the back door at night, as I was able to do as late as the 1980s, when the cave was still connected with others at the back end, and not well sealed as it is today. Especially considering that some of the ghosts (now adding the visual component) are said to walk through walls. That sounds to me like someone emerging from an opening into the cave proper. All it would take is an incident or two like this to get the stories going. (STC)

Giardiasis.Nasty protozoal disease of sewer explorers.

Glenwood Shale.A layer of green shale about 3 feet thick, lying between the St Peter Sandstone and the Platteville Limestone. Easily dislodged, it forms the grody green material over which you must frequently slither.

GLVs.Grim Little Voids, a phrase coined for erosional pockets in sewer walls, especially in the deep sewers.

Golden Age of Sewer Caves.The WPA era, in the 1930s, when so many Twin Cities caves, like Channel Rock, were found during the construction of riverbank interceptors. This same kind of thing happened in other cities around the nation.

Grand Interceptor.What a project that was! The 13-foot diameter double barrels cut with hydraulic lances up to 200 feet below Marshall Avenue, leading out to the Pigs Eye sewage treatment plant, which became operational in 1938.

Great Cave Springs I have Known.Well, that would include the ceiling spring in Schieks Cave, dubbed Little Minnehaha Falls by sewer workers long ago. See Thermal Anomaly.

Great Tunnel Springs I have Known.We are used to seeing nice springs of water on the surface. Historically, I believe the first great tunnel spring was the Big Spring that erupted inside the tunnel being constructed under the Severn River in Britain, in 1879, and which caused the chief engineer Fox, and his intrepid diver Lambert, so much grief to stem the flow. In the TC Metro, I have encountered very powerful floor springs in various tunnels, but perhaps the most showysometimes with a peacocks tail of rainbow huesare the fire-hose springs of the deep interstate drainage tunnels, very powerful jets of water shooting from the walls of tunnels. The tunnels have to be pretty deep to provide such a steep hydraulic gradient.

Gypsum.A mineral not often found in Minnesota caves owing to the humidity.

Herds, exploratory.Years ago, when part of an on-line group, I was reproached for not coughing up subterranean locations on demand to people I had never met, and was told that I had no right to exclude them from various places, etc. (But even if you did roll over and spill your guts, there was little gratitude anyway, the tunnel or whatever would soon appear on a website as their discovery.) So I had to laugh sometime later when those very same individuals complained about the herd that followed themwhy should they allow this new group into their caves, tunnels, etc? Youve got to realize, everyones group is a herd to someone else, and people often dislike the herds that come after them, no matter who they are.

Hothouse Fauna.A term coined by the biospeleologist Bill Elliott to refer to the dystrophic ecosystems of caves flooded with raw sewage, and which usually have the associated elevated air temps. The best local example is Schieks Cave.

Ice-Cream Cone Animal.The largest fossil in the Platteville layer is the well-known giant ice-cream cone shaped mollusk Endoceras, as long as 13 feet, which you occasionally find in the Mississippi gorge, where they have been confused with petrified logs. (STC)

Interceptor.Strictly, sanitary sewers that run parallel to water courses, thus intercepting sewage that would ordinarily flow into, and pollute, these surface waters.

Invert.The floor of a sewer, usually made of higher quality materials to retard erosion.

Inverted Siphon.A U-shaped pipe, higher at one end, which, under pipe-full conditions, allows fluids to cross under various obstacles. The most famous local examples are the ones at the Lake Street bridge in Minneapolis, and at Navy Island in St Paul. Dont try to walk under the river using them, even if one barrel is empty, because it could suddenly fill up!

Lagering.Prior to 1840, according to many histories of the subject, there were no breweries in America producing the German-style lager beer. Lager beer differed from the prevalent English and American beers, such as ale, in that the lager yeast fermented at the bottom of the vat, rather than the top, and the beer required lagering, or storage, for several months at lower temperatures. In the old days, lager beer could only be brewed during the winter months, when cellar temperatures were sufficiently low. But in northern states, such as Minnesota, where natural ice was readily available, ice cakes could be harvested from nearby lakes and rivers in winter and stacked in caves, allowing brewing all year round to meet the growing demand. (STC)

Liesegang Bands.The paleo water-tables left bizarre reddish redox discolorations in the St. Peter Sandstone, especially near its top, helping you know where you were while exploring the sandrock labyrinths. (STC)

Macaroni.The terra cotta tiles used to line some sewer walls in the 1920s, which had the appearance of those funny pasta shapes found in your grocery store. (STC)

Mannings Number.Describes the roughness of a channel, used in the equations of hydraulic engineers.

Medusa.Outside the realm of mythology, applied to speleothems that look like a medusas head, with snaky locks of dripping stalactites. The most famous local medusa, of course, is the Black Medusa of Schieks Cave.

Metcalf & Eddy.The classic textbook for sewer engineers, the older editions of which are actually more useful when youre studying the older sewers.

Mines of Moria. Something out of the Tolkien stories, and frequently spraypainted on cave walls back when his books were all the rage.

Mushroom Gardens.The Greeks and Romans were fond of eating mushrooms collected in woods and meadows but it was not until about 1650, in Paris, that one particular species, the White Mushroom (Agaricus bisporus), was actually domesticated, or cultivated. Other species had been cultivated in the Orient many years earlier. The White Mushroom thrived on horse manure, but not as well on the manure of other animals. About 1800, Parisians found that mushrooms could be grown in the dark, in the subterranean stone quarries that honeycombed their city, which provided even temperature year round. Mushroom cultivation did not reach the United States until 1865. In the 1880s, there was an abortive attempt by the Mammoth Cave Mushroom Company in Kentucky to raise mushrooms in that cave, the product being served up at the Mammoth Cave Hotel and shipped to Eastern cities.

The original mushroom farmers in St. Paul were Frenchmen who had seen mushrooms growing in the caves under the sewers of Paris. Interviewed on at least two separate occasions by newspaper columnist Gareth Hiebert (Oliver Towne), the St. Paul mushroom farmers stated that their predecessors began the local industry in the 1880s. The last cave ceased production in the 1980s during the creation of Lilydale Regional Park. (STC)

Nightclubs in Urban Caves.Mushroom Valleys nightclub era began as national prohibition (1919-1934) was winding down. There were two nightclubs here in the 1930s, Mystic Caverns and Castle Royal. A local mushroom grower recalled the bumper-to-bumper cars that poured past here day and night to those nightclubs. Oliver Towne called Mushroom Valley One of the oddest night club belts in the world.

Mystic Caverns is forgotten today, but was beloved in the 1930s. The most novel caf and night club in the country was opened on April 8, 1933, about the same time that the classic version of King Kong, starring Fay Wray, hit the movie theaters. Garish newspaper advertisements for Mystic Caverns, with leering skulls, promoted St. Pauls Underground Wonderland, advising readers to See the Beautiful Silver Cave and the Rainbow Shower of 2,000 Mirrors. Dine, Drink, and dance to the rhythmic tunes of Jack Fosters Ten Cavemen, spelling out the location exactly: Cross the Wabasha Street Bridge at the new St. Paul Courthouse. Travelup the river road under the High Bridge to the huge Neon Skull and Crossbones.

After its glory days, Mystic Caverns was used for potato storage and in its misunderstood old age was dubbed Horseshoe Cave by the cavers of the 1980s, unaware of its romantic past. In the 1990s, I diligently examined the infinite palimpsest of graffiti on the caves walls, especially in the former ballroom, hoping for old signatures (or any artifact) from the nightclub era, but could find nothing really convincing. It had been stripped bare, like the fan dancers who had wowed crowds more than half a century earlier.

The other big 1930s nightclub was Castle Royal, proclaimed The Worlds Most Gorgeous Underground Night Club, on what is now South Wabasha Street. The cave consists of several parallel passages connected by cross-cuts. Originally a mushroom cave, it was acquired by William Lehmann, who achieved local fame as the Mushroom King, as noted above. On October 26, 1933, after spending $150,000 on the place, he opened a nightclub in the cave, Castle Royal, with a fancy, patterned brick faade that you can still admire today. Mushrooms, not surprisingly, loomed large in the dollar menu that he touted. The chandeliers, fountains, and tapestries that graced the establishment came from the recently demolished Gates mansion, as in Bet a Million Gates, the largest manufacturer of barbed wire in the nation. The ceiling was stuccoed to prevent the incessant rain of sand grains that would otherwise give you that gritty feel while eating. Doorways were carved out in the shape of mushrooms. In the Big Band era, performers like Cab Calloway, the Dorsey Brothers, Harry James, and the Coronado Orchestra played there. And of course there are the gangster stories. The nightclub went bankrupt in 1940, and eventually the cave was used for other purposes. It has been brilliantly restored by Bremer Construction (STC)

Old Ones.Borrowing a bit of Lovecraftian lore, we began applying this term to really old visitors to our caves and tunnels. Increasingly, anyone who explored these places before the invention of websites, leaving only their crude wall markings. I saw a good example of this in Santas Cave, where the walls were smoked over from past fires, and the pre-smoke graffiti was the really old stuff. Cf. Beaker Folk.

Oneota.The mazy caves of the Prairie du Chien dolomites, the classic type of Wisconsin caves, but also found here in Minnesota, as at Miles Cave, in the city of Hastings.

Ossuary.Some of the drier sandrock passages hereabouts are replete with bones, especially of the raccoon. A good local example is the spiraling side-passage of the Koch tunnels.

Outfall.A sewer exit.

Overbreaks.Overbreaks are a by-product of tunnel construction. Located outside the concrete tunnel linings, in the surrounding sandrock, overbreaks are the most remote physical spaces under the city of Minneapolis. The overbreaks ranged in size from tight belly crawls to Gothic cathedral passages 15 feet high, but most of them involved painful hands and knees crawling, for which I evolved a special marsupial pack that slung from my belly, to carry basic supplies. My hope was to use this secret system of dry passages to get from Schieks Cave to other caves depicted on the sewer plats, such as the Nicollet Mall cave, mentioned in a 1929 newspaper clipping. (STC)

Paleosol.--Buried soil layers, the most important of which for UE purposes is the 1935 beer-can horizon (there were only beer bottles before that). In the 1960s we have the Pepsi Generation and other Beaker Folk.

Pigeonhole.The microfiche file at St Paul Public Works dept containing the really old, really good stuff. I found the oldest map of Fountain Cave there, dating to 1880.

Piping.Natural caves form in the St. Peter Sandstone by a process known as piping, a form of erosion caused by flowing groundwater. Piping forms two different kinds of cave in the St. Peter: tubular caves, best exemplified by Fountain Cave in St. Paul, and maze caves, best seen in Schieks Cave under downtown Minneapolis. The term was borrowed from civil engineering practice in the late 1940s. It was used originally to refer to the pipe-shaped voids formed by seepage of water around failing dams. (STC)

Poop Castle.Large, elaborate, house-like sewer structures of unknown function, after the one found in the overbreaks en route to Schieks Cave. Sometimes you have to dig about in the old textbooks to find a parallel.

Portaging.When the sewer maps showed two sandrock tunnels approaching very closely under certain conditions, there was often a connection between them. Over time, I developed skill in predicting and using portages to the point where I began to fancy that I could almost walk through solid rock. Ultimately, it had to do with the geology. You wouldnt expect to find this generous connectivity in harder rock types like schist (as under Manhattan) or limestone (as under St. Louis), because they are more expensive to excavate. (STC)

RCP.The abbreviation for Reinforced Concrete Pipe. Early on, I determined that my tolerance level for crawling through small pipes over long distances was about 21 inches. Sure, its easy to fit through smaller openings, but Im talking about, like, being able to tolerate several city blocks of crawling that diameter. The really big RCPs, having nothing to look at while you hike, are conducive to abstract hydrological thought.

Rinkers Revenge.Andrew Rinker, Minneapolis city engineer for 36 years, was the Father of the North Minneapolis Tunnel (NMT), where this nasty gastrointestinal illness was frequently contracted. Entering NMTor even getting near itwas a prescription for the ailment, at least for me. Never on any occasion that I became sick did I recall having actually swallowed sewage while in the tunnel. I did notice, however, that whenever a beam of light illuminated the tunnel, the air was laced with shining droplets and rainbows. And once, leaning down near the surface of the stream, I got a soapy taste, as if the air I inhaled contained enough droplets to generate taste. I later learned that these infectious droplets are well known to aerobiologists as coliform aerosols, and contain fecal bacteria, among other things. (STC)

Rockets & White Mice.The traditional sanitary tokens, indicative of flooding by raw sewage, and found in Schieks Cave in great numbers. (STC)

Rotten-Egg Gas.Known to the chemist as hydrogen sulfide, it can be as deadly as hydrogen cyanide, but has the merit (?) of being odorous, giving you a warning. It tends to bubble out of solution where sewage flows turbulently. It is also very corrosive of metallic sewer fixtures and concrete, once it has oxidized to sulfuric acid.

Rusticles.Most of the reddish color seen in ordinary cave deposits is due, not to iron, but to humic acids of various descriptions. But some formations consist entirely of reddish iron minerals, and these are the rusticles.

St. Peter Sandstone.The St. Peter Sandstone is the greatest layer in terms of subterranean exploration owing to its ease of excavation. Its safe to say that without the St. Peter there would be very little subterranean exploration. The pioneer geologist David Dale Owen officially named this rock in 1852 for outcrops near Fort Snelling, along the St. Peters Rivernow the Minnesota River. The St. Peter layer has an average thickness of about 100 feet regionally. However, its about 150 feet thick at its type section at Fort Snelling and it ranges up to 500 feet thick at Joliet, Illinois, as determined from drilling records. That leaves plenty of three-dimensional volume for caves and tunnels. While this layer is quite uniform, there are subtle ways of telling approximately where you are inside it, vertically speaking, when you are walking through unlined tunnels that pass through it. If, for example, you see wild red swirls of iron pigmenttechnically called Liesegang bandsleft by groundwater, you know that you are somewhere near the top of the layer, at least in the Twin Cities. Near the bottom of the St Peter layer, by contrast, the sandstone is much siltier.

The St. Peter is very extensive for a single formation, covering nearly a quarter million square miles in the Midwest. St. Paul was known to the Dakota Indians as White Rocks because of this glaringly white layer, exposed in its river bluffs. Crystal City, near St. Louis, Missouri, was named for the fact that the Pittsburgh Plate Glass Company used the St. Peter sand that outcropped there for making glass, as was also done at Ottawa, Illinois, and at Clayton, Iowa, among other places. Locally, the sand was also used for glass making, as at the Ford Sand Mines under St. Paul, with its miles of passages. To the south, the layer extends into Arkansas, Oklahoma, and Tennessee, and as far east as Ohio and Kentucky, where it sometimes contains oil and gas.

The St. Peter has an almost saintly purity throughout most of this range, suggesting that it has been recycled from older sandstones, geologically winnowed of its impurities. The St. Peter is called a sheet sand, meaning that it was laid down flat, like a sheet, over large areas, by a warm shallow sea that invaded the continent from the south. It was the last major sandstone layer to be deposited in the Upper Mississippi Valley. Most importantly, the St. Peter Sandstone, in the Minnesota part of its range, lacks natural cementation, hence it is friable, and easily excavated. Historically, it was often compared to loaf sugar, a commodity rarely seen nowadays. In other locations, however, the St. Peter has plenty of cement holding the grains together, as at Starved Rocks State Park in central Illinois, where this sandstone stands proud as high cliffs. (STC)

Sandhogs.Tunnel diggers! Around the Twin Cities, where the tunnels are excavated through the bedrock sandstone, the name is unusually apt, but they are called sandhogs even under Manhattan, where the predominant rock types are schist, marble, etc.

Scolithos.A trace fossil found in the St. Peter Sandstone, often seen as a U-shaped discoloration in rock outcroppings, representing fossil worm burrows. (STC)

Sedimentology of the sewers.During a trip through the Bassett Creek Tunnel in Minneapolis years ago, I mapped out the sediments with the aim of investigating the layering and what that might say about storm events. I found the sewer stratigraphy fairly trivial, but the horizontal distribution of sediments was especially interesting. Basically, sediments of large grain size (sand and gravel) were located near the active water inputs to the tunnel, but as I progressed downstream from these inputs, the grain size decreased, reflecting a transport process where the heavier sediments dropped out first. Eventually, beyond the belts of sand, silt, and finally mud, Id encounter bare tunnel floor, which would last until the next input, where the sandbars started again. The most famous sandbars were dubbed The Spice Islands, owing to their not-unexpected fragrance. If the sandbars have incorporated substantial organic matter, they can become whistling sandbars, as they periodically release putrefactive gasses (STC)

Sewers, Classification of.There are two kinds of sewers, sanitary and storm. The term sanitary is a euphemism because it refers to raw sewage, which most of us would consider unsanitary. Its sanitary in the sense that its not running into nearby water bodies and polluting them, but going instead to a sewage treatment plant. Sanitary sewers are sometimes called interceptors because they intercept raw sewage that would otherwise flow into water bodies. On the other hand theres the storm sewer, often called a storm drain, which carries rainwater to water bodies by means of an exit, called an outfall. Even when its not raining, however, most storm drains carry groundwater that has seeped into them.

In the bad old days, most sewers did double duty, leaving water bodies severely polluted, but here in the Twin Cities, the separate system was introduced in the 1930s, with the municipal treatment plant at Pigs Eye, near St Paul, becoming operational in 1938. It treated the sewage of both Minneapolis and St. Paul. Occasionally, however, the two kinds of sewer would still overflow into one another, so to further reduce river pollution an on-going effort has been made in recent decades to separate them even more thoroughly. (STC)

Sewer Conics.Apollonius of Perga, several centuries BC, first laid out the possible sections of a cone, which school children have minded ever since. The several Orders of Sewer Architecture are Box, Egg, Elliptical, Gothic, etc.

Shellrock.As depicted in cross-sections by well-drillers in the early decades of the last century, this was the name applied to the Mifflin Member of the Platteville Limestone, because it tends to split into thin layers, owing to the shaly partings in this rock. To a geologist, however, the term shellrock would refer to a rock full of fossil shells, like a coquina.

Snottites.This term, applied to jelly stalactites in sewers, was borrowed from Cueva de Villa Luz, in Mexico, by yours truly, and refers to what sanitary engineers would call pendant sewer slime (see Biofilms). The really big difference is that these slimes live off the beer aerosols and are non-acidic, whereas the originals eat rock and are highly acidic.

Soapstone.As depicted in cross-sections by well-drillers in the early decades of the last century, this was the name applied to the Glenwood Shale.

Spiral Helix Era.Another name for the Great Depression, during which the great spiral flight sewers of the Twin Cities were built under the direction of George Shepard (yes, he of Shepard Road), one of the great architects of the underground St Paul.

Stone Teepees.A rough transliteration of what Native Americans called the local natural caves.

Sump.Place where the water-level in a flooded passage meets the ceiling, preventing further exploration, except by diving.

Thermal Anomaly.Inside Schieks Cave there was a concrete chamber that resembled a baseball dugout. The chamber contained a ceiling spring that was dubbed Little Minnehaha Falls by sewer workers long ago, and it was labeled as such on Dornbergs 1939 map. Using a thermometer, I took the temperature of Little Minnehaha Falls and found her very feverish. The groundwater temperature was 19C, more than twice the expected value at this latitude, and warmer even than surface water for that time of year. I speculated that this thermal anomaly could be the result of heat generated by human activities in a densely urbanized area. (STC)

Toshers.Henry Mayhews classic work on obscure London trades, published in 1851, described the toshers who daily searched the London sewers for valuables as a means of livelihood. (STC)

Tumblerock.As depicted in cross-sections by well-drillers in the early decades of the last century, this was the name applied to chunks of Platteville limestone that had fallen off the riverbluffs. The best tumblerock can be seen at all sorts of rakish angles while driving along Shepard Road north of the High Bridge.

Tunnel, Light at the End of.Ive always hated this expression. If you were exploring a tunnel, wouldnt you want it to go on forever? Of course, not to be confused with Gegenschein (which see).

Tunnel Fever.See Rinkers Revenge.

Tunnel Vertigo.Dizziness brought about by lengthy hiking through monotonous concrete pipes with dim lights.

Unktahe.The Dakota god of water and the underworld. Historically, the Camp Coldwater spring in Minneapolis was associated with Unktahe, who was often visualized as a fish or serpent. Mary Henderson Eastman wrote in 1849, Unktehi, the god of the waters, is much reverenced by the Dahcotahs. Morgans bluff, near Fort Snelling, is called Gods house by the Dahcotahs; they say it is the residence of Unktehi, and under the hill is a subterranean passage, through which they say the water-god passes when he enters the St. Peters [Minnesota River]. He is said to be as large as a white mans house. But Unktahe was also associated with Carvers Cave by some elders. Gary Cavender, who identified himself as the spiritual leader of the Prior Lake Shakopee Dakota band, said that he was warned by his grandfather never to go deep into Carvers Cave, because Unktahe resides in the lake that fills the cave. (STC)

Vermiculations.Small squiggles of dirt on the walls of caves or sewers, sometimes resembling hieroglyphics. They are deposited from the surface tension of condensation drops, which gives them a rounded shape, and are often confused with floodmarks. Specialists have developed elaborate classifications for vermiculations, somewhat feline in character, dividing them into leopard spots, tiger stripes, etc.

Victorian Show Caves.There are three natural caves in the Twin Cities area that were developed as show caves (where tourists pay to get in): Fountain Cave (early 1850s), Carvers Cave (late 1860s), and Chutes Cave (late 1870s). The large scale development of show caves in the United States did not occur until after widespread adoption of the automobile, allowing tourist access to hitherto remote rural areas, where many of these caves are located. While sometimes called commercial caves, the latter term is not as accurate because it includes other commercial uses of caves, such as mushroom gardening.

Weils Disease.A rat-borne illness of sewer workers, caused by the urine of those benighted creatures.

Whalebacks.Linear push-ups in the floors of large tunnels where built over wetlands or expansible soils. Classic examples are the whalebacks of the Canal Street Sewer, in St. Paul. Eventually, they break open, like a festering boil, leading to complete destruction of the invert.

Winchell Trail.Opened by the Minneapolis Park Board in 1915, it runs for several miles along East River Road, following the path that geologist Winchell would have used in his studies of the postglacial retreat of St Anthony Falls. Its relevant here because it runs past many interesting spelean features, such as Channel Rock Cavern, Minneapoliss largest sinkhole, and some nice ice caves with ice stalagmites. The trail is the scene of both beauty (so much so, that the V.O. Hammon Co made postcards of the scenes in the 1920s) and butchery (so much so, that the trail runs like a scarlet thread thru city history).

Winogradsky Column.A standard piece of equipment in microbiology labs, allowing for the growth of anaerobic bacteria, and named after the Russian bacteriologist Winogradsky, who pioneered its use in the 1890s. Its relevant here because there seems to be something like this going on with sewer sediments. In the Minneapolis mill tunnels, for example, theres red (oxidized) layered over black (anoxic) sediments.

Wizards Table.The six manhole towers in the Dupont segment took on a new significance. We began calling them teakettles from their shape, but more especially from the boiling noise they made, caused by the sound of rushing water at deeper levels. We tried to pry off a few of the teakettle lids, but with no success. It wasnt until the Schieks Cave project years later that I learned the true significance of these teakettles. At the sixth and largest Dupont teakettle, however, where the tunnel swerves under the Olson Memorial Highway, I was amazed to see a pinhole camera effect, created by light streaming through ventilation holes in the street above. Most amazingly, I could actually see images of aircraft, about an inch long, passing in the skies above, crossing over the top of the manhole lid. I dubbed this lid the Wizards Table. While I have seen this manhole-pinhole effect in other sewers over the years, this one was by far the most exquisite. (STC)

Zebra Flowstone.Vertically striped black and white, or zebra, flowstone. The black mineral is probably manganese. When present over a considerable stretch of tunnel, as in the old Chicago tunnel, they form candystripe tunnels.