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70+ Cave Features For Fantasy Worldbuilding36 Min Read

70+ Cave Features For Fantasy Worldbuilding36 min read

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Stalactites, stalagmites, caverns, and crystals! Welcome back, Outlander, to the 12th entry in Mythic Ecology, my series on how learning real-world landscape features can enrich our fantasy worldbuilding and storytelling. In this post I return to my minimalist framework for Dungeon Masters, Game Masters, fiction writers, and similar worldbuilders to merge the realms of general myth and geomorphology. Last entry I took a detour to update my D&D 5e Free Resource Compendium. As I resume my journey sketching a framework for designing Yridia, my unique D&D 5e fantasy world, let’s learn some cave terms, with a visual guide!

All the images herein I use for educational and entertainment purposes, I claim no rights to any of them. For corrections or content removal requests, hit my contact page. Special thanks go to Jim Belt of Start Caving for “Types of Cave Passages: Advanced Illustrated Guide“, a vital resource for this entry.

Part 0: Mythic Ecology For Fantasy Worldbuilding & Storytelling
-Settlements
-Omens
-Overlooks
-Passageways
-Abyss
-Battlegrounds

Part 1: Caves 101
Cave
-Cavern
-Grotto

Part 2: Cave Ecologies
Endogean (Entrance Zone)
Parahypogean (Twilight Zone)
Hypogean (Dark Zone)
Deep Hypogean (Underdark Zone)

Part 3: Cave Form Categories
Anchialine Caves
Corrasional Caves / Erosional Caves
Fracture Caves
Glacial Cave
Primary Caves
-Rock Shelters
-Sea Caves / Littoral Caves
-Solutional Caves / Karst Caves
-Talus Caves

Part 4: Cave Passage Patterns I
Anastomotic Caves
Angular Network Caves
Branchwork Caves
Pit Caves
-Ramiform Caves
-Spongework Caves

Part 5: Cave Passage Patterns II
Phreatic Passages
Avens / Bell Holes
Soluble Bed
–Sump
-Vadose Passages
–Keyhole Passages
–Drain Shaft
–Breakout Chamber / Dome
-Epiphreatic Passages
–Intertidal Passages
-Fault-Formed Passages
-Fissure/Rift Passages

Part 6: Dripstone Speleothems
Speleothems
Dripstones
Stalactites
—-Chandeliers
—-Helictites
—-Soda Straws
—Stalagmites
—-Broomstick Stalagmites
—-Fried Egg Stalagmites
—-Totem Pole Stalagmites
—Stalagnates / Columns

Part 7: Flowstone Speleothems
Flowstones
Draperies
—Rimstone Dams / Gours
—Stone Waterfalls

Part 8: Crystal Speleothems
-Cave Crystals
—Anthodites
—Cryogenic Calcite Crystals
—Dogtooth Spar
—Frostwork
—Moonmilk

Part 9: Speleogens & Exotics
Speleogens
Boneyard
Boxwork
Pillars
–Scallops
-Exotics
–Calcite Rafts
–Cave Peals
–Cave Popcorn / Coralloids / Cave Coral
–Hells Bells
–Stottites / Snoticles

Part 10: Pits & Shafts
Abime / Pit Caves / Pot Caves / Shaft Cave / Jama
Blowhole
Cenote
Foiba
Karst Fenster
-Moulin / Glacier Mill
-Panhole / Weathering Pans
-Scowle
-Sinkhole

Part 11: Special Cave Features
Boulder Choke
Cave In
Cave Window
-Sunholes
-Subterranean Tunnel
-Subterranean Waterfall

PART 0: MYTHIC ECOLOGY FOR FANTASY WORLDBUILDING & STORYTELLING

Let’s revisit my minimalist framework for my worldbuilding. The six archetype tags with which I will flag all the various real-world land features in my Mythic Ecology Series:

1. Settlements: habitable regions of either Work or Play, Familiar or Exotic, offering diverse narrative functions: a Day in the Life, Home Base, Personal Reasons, Gathering Supplies. Can subvert tropes with Ruins or Escape.
2. Omens: sensational, temporal, or particularly pointed features that offer narrative functions of forshadowing, and good or evil portents. Can subvert tropes with a Wild Goose Chase.
3. Overlooks: sites of magnitude and grandeur, living monuments which can function narratively for finding resolve, invoking spirits, or as a Call to Adventure. Can subvert tropes with Dread or Betrayal.
4. Passageways: transitional journeylands, including magical portals, functioning narratively for initiation and return, thresholds and tests, shortcuts and setbacks.
5. Abyss: a void or confined space presenting scarcity or temptation, desperation and danger. Can subvert tropes with a Timely Rescue or Secret Refuge.
6. Battlegrounds: sites fit for epic, sprawling encounters and climax conflicts. Can subvert tropes with Alternative Solutions.

Feel free to submit your own ideas, or draw outside the lines. Alright, let’s see how caves fit in.

PART 1: CAVES 101

Otherworldly Incantations Caves Worldbuilding Cover
Cavea natural underground space large enough for a person to enter.
[Settlements, Omens, Overlooks, Passageways, Abyss, Battlegrounds]
Otherworldly Incantations Cave Worldbuilding Cave
Caverna cave chamber.
[Settlements, Omens, Passageways, Abyss]
Otherworldly Incantations Caves Worldbuilding
Grotto – an inhabitable natural or artificial cave, often near water, and sometimes partially flooded.
[Settlements, Omens, Overlooks, Passageways, Abyss, Battlegrounds]

PART 2: CAVE ECOLOGIES

Otherworldly Incantations Cave Worldbuilding Entrance Zone

Endogean (Entrance Zone) the parts of caves interacting with surface soils through cracks and rock seams, groundwater seepage, and root protrusion.
[Settlements, Omens, Passageways, Abyss, Battlegrounds]

Otherworldly Incantations Cave Worldbuilding Twilight Zone

Parahypogean (Twilight Zone) the threshold portions near cave mouths extending to the last penetration of sunlight.
[Settlements, Omens, Overlooks, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Dark Zone

Hypogean (Dark Zone) – “true” cave environments, can have regular contact with the surface via wind and underground rivers, animal migration, or almost entirely isolation.
[Settlements, Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Darkest Zone

Deep Hypogean (Underdark Zone) can host autonomous ecologies whose primary energy sources comes from chemical energy harvested by bacteria from minerals like limestone, rather than from sunlight. In D&D mythos this could correspond to the “Underdark”.
[Settlements, Omens, Overlooks, Passageways, Abyss, Battlegrounds]

PART 3: CAVE FORM CATEGORIES

Otherworldly Incantations Caves Worldbuilding Anchialine Caves

Anchialine Caves caves formed in mixtures of freshwater and saline water, usually coastal. Frequently signifies underwater caverns.
[Settlements, Omens, Overlooks, Passageways, Abyss, Battlegrounds]

Otherworldly Incantations Cave Worldbuilding Corrasional Caves

Corrasional Caves / Erosional Cavescaves formed entirely by erosion from flowing streams carrying rocks of any kind, and sediment, along a fault or joint. Also includes aeolian caves carved by wind-born sediment. Often erosion expands smaller openings arising from solutional processes.
[Settlements, Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Fracture Caves

Fracture Caves – caves formed when layers of more soluble minerals, like gypsum, dissolve away between layers of less soluble rock, causing fractures and collapses in blocks of stone.
[Settlements, Omens, Passageways, Abyss]

Otherworldly Incantations Tundra Worldbuilding Glacial Cave

Glacial Cavecaves formed within glacial ice. Related to moulin.
[Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Primary Caves

Primary Caves caves formed from the same surrounding rock. This includes lava tubes arising as lava solidifies and hollows beneath the crust, as well as blister caves, tufa caves, and reef caves.
[Settlements, Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Rock Shelter

Rock Shelterssimple, often shallow cave-like openings at the base of a bluff or cliff. Produced by bedrock erosion in insoluble rock, such as where sandstone overlies shale. Whereas normal caves have more depth than width, rock shelters have more width than depth.
[Settlements, Passageways, Abyss]

Otherworldly Incantations Coastal Worldbuilding Sea Cave

Sea Caves / Littoral Caves caves formed primarily by erosion from the sea’s wave action; they may form along present coastlines or remain on former coastlines.
[Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Karst Cave

Solutional Caves / Karst Cavescaves formed in soluble rock, typically limestone, but sometimes also chalk, dolomite, marble, salt, or gypsum. Formed as natural acid in groundwater seeps through bedding plans, faults, or joints, and dissolves open cracks which become caves. The most common cave type.
[Settlements, Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Talus Caves

Talus Cavescaves formed by openings among random heaps of large, fallen boulders, often at the base of cliffs. Related to scree.
[Settlements, Omens, Passageways, Abyss]

PART 4: CAVE PASSAGE PATTERNS I

Otherworldly Incantations Cave Worldbuilding Passage Patterns I
Otherworldly Incantations Cave Worldbuilding Anastomotic Caves

Anastomotic Caves passages separating then meeting further down drainage, resembling braided streams. Typically formed along one bed or structure, rarely crossing into upper or lower.
[Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Network Cave

Angular Network Caves high, narrow, straight passages persisting in widespread closed loops. Formed from intersecting fissures of carbonate rock with fractures expanded by chemical erosion.
[Omens, Passageways, Abyss]

Otherworldly Incantations Caves Worldbuilding Branchwork Caves

Branchwork Caves passages converging downstream as tributaries, resembling dendritic streams. Most common cave passage form, associated with sinkholes; each branch has a separate recharge source.
[Omens, Passageways, Abyss]

Otherworldly Incantations Caves Worldbuilding Pit Caves

Pit Caves passages appearing as vertical shafts, such as vertical caves, potholes, or pits, rather than horizontal passages. May or may not be associated with other structural patterns.
[Omens, Overlooks, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Ramiform Caves

Ramiform Caves passages forming as randomized three-dimensional rooms resembling irregular large rooms and galleries. Formed when a rising water table erodes carbonate rock with hydrogen-sulfide enriched water.
[Settlements, Omens, Passageways, Abyss, Battlegrounds]

Otherworldly Incantations Cave Worldbuilding Spongework Caves

Spongework Caves passages manifesting in a random three-dimensional pattern, resembling a sponge. Formed when solution cavities mix with chemically diverse water.
[Settlements, Omens, Passageways, Abyss, Battlegrounds]

PART 5: CAVE PASSAGE PATTERNS II

Phreatic Passages – passages in the zone of underground water, saturated beneath the water table.

Otherworldly Incantations Cave Worldbuilding Phreatic Passages
Otherworldly Incantations Cave Worldbuilding Bell Holes

Avens / Bell Holes vertical tubes in a cave ceiling formed by water swirling under extreme pressure.
[Omens, Overlooks, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Soluble Bed

Soluble Bed formed when water dissolves carbonarite rock then the water table drops, leaving a wide and low space with smooth ceiling and floor.
[Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Sump

Sump – a cave passage submerged in water, with either static or active flow.
[Omens, Passageways, Abyss]

Vadose Passages – passages in the zone above the water table, comprising a cave drain complex. Formed by free-flowing water, which creates channels like shafts and canyons. Narrow passages indicate rapid incision, whereas wide ones indicate stable water levels.
Otherworldly Incantations Cave Worldbuilding Vadose Passages
Otherworldly Incantations Cave Worldbuilding Keyhole Passage
Keyhole Passages keyhole-shaped passages carved out by streams, sometimes too narrow to navigate.
[Omens, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Drain Shafts
Drain Shaftvertical, straight, and narrow shafts, sometimes large, that can connect horizontal passages on different levels, carved out as water trickles along break lines and fractures.
[Omens, Overlooks, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Breakout Chamber
Breakout Chamber / Domepassages formed by the collapsed ceilings of phreatic tubes, with telltale floors and sometimes vault-like shapes at the top.
[Omens, Passageways, Abyss]
Epiphreatic Passagesthe floodwater zone between the phreatic and vadose zones, flooded during high water and drained during low water, containing either water under pressure and free-flowing water depending on the cycle.
Otherworldly Incantations Cave Worldbuilding Intertidal Passage
Intertidal Passagespassages formed as water floods in and out of the cave.
[Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Fault and Fissure Passages
Otherworldly Incantations Caves Worldbuilding Fault Passage
Fault-Formed Passagespassages with large stretches of straight rock formed by seismic activity, indicated by planar hanging walls of split rock.
[Omens, Passageways, Abyss]
Otherworldly Incantations Caves Worldbuilding Rift Passage
Fissure/Rift Passagesstraight and narrow passages more deep than wide. Started as rock splits or cracks then develops along the joint, wearing out and widening. Come in both phreatic (pressurized) and vadose (slow erosion) forms.
[
Omens, Passageways, Abyss]

PART 6: DRIPSTONE SPELEOTHEMS

Otherworldly Incantations Cave Worldbuilding Speleothems
*A Stalactite *B Soda straws *C Stalagmites *D Coned stalagmite *E Stalagnate or column *F Drapery *G Drapery *H Helictites *I Moonmilk *J Sinter pool, rimstone *K Calcite crystals *L Sinter terrace *M Karst *N Body of water *O Shield *P Cave clouds *Q Cave pearls *R Tower cones *S Shelfstones *T Baldacchino canopy *U Bottlebrush stalactite *V Conulite *W Flowstone *X Trays *Y Calcite rafts *Z Cave popcorn or coralloids *AA Frostworks *AB Flowstone *AC Splattermite *AD Speleoseismites *AE Boxworks *AF Oriented stalactite *AG collapsed rubble
Speleothems – cave formations created by gradual accretion of secondary minerals into deposits, typically in limestone or dolomite solutional caves. Usually a translucent white color from calcium carbonate.
Dripstones calcium carbonate structures. Includes stalactites, stalagmites, and stalagnates.
Otherworldly Incantations Cave Worldbuilding Stalactites
Stalactites – pointed pendants growing down from cave ceilings, typically conical.
[Omens]
Otherworldly Incantations Cave Worldbuilding Chandeliers
Chandeliers – complex clusters of decorative ceiling stalactites.
[Omens]
Otherworldly Incantations Cave Worldbuilding Helictites

Helictites – stalactites with a central canal with twig-like or spiral projections that seemingly defy gravity. Includes ribbon helictites, saws, rods, butterflies, hands, curly-fries, “clumps of worms”.
[Omens]

Otherworldly Incantations Cave Worldbuilding Soda Straws
Soda Strawsvery thin but long stalactites with an elongated cylindrical shape.
[Omens]
Otherworldly Incantations Cave Worldbuilding Stalagmite
Stalagmites – the upward protrusion counterparts of stalactites, often blunt mounds.
[Omens]
Otherworldly Incantations Cave Worldbuilding Broomstick
Broomstick Stalagmites – very tall and spindly stalagmites.
[Omens]
Otherworldly Incantations Cave Worldbuilding Fried Egg Stalagmite
Fried Egg Stalagmites – small, typically wider than tall.
[Omens]
Otherworldly Incantations Cave Worldbuilding Totem Pole
Totem Pole Stalagmites – tall and shaped like totem poles.
[Omens]
Otherworldly Incantations Cave Worldbuilding Stalagnates
Stalagnates / Columns – pillars formed when stalactites meet stalagmites, or stalactites reach the cave floor.
[Omens]

PART 7: FLOWSTONE SPELEOTHEMS

Flowstones – sheet-like structures found on cave floors and walls.
Otherworldly Incantations Cave Worldbuilding Draperies
Draperies wavy sheets of calcite hanging downward, resembling thin curtains. Includes “bacon”, with colorful bands within sheets.
[Omens]
Otherworldly Incantations Cave Worldbuilding Rimstone Dam
Rimstone Dams / Gours – barriers, possibly containing water, which occur at stream ripples.
[Omens, Abyss]
Otherworldly Incantations Cave Worldbuilding Stone Waterfall
Stone Waterfalls – formations simulating frozen cascades.
[Omens]

PART 8: CRYSTAL SPELEOTHEMS

Cave Crystals – crystalline structures found in caves.
Otherworldly Incantations Cave Worldbuilding Anthodite
Anthodites – flower-like clusters of aragonite crystals.
[Omens]
Otherworldly Incantations Cave Worldbuilding cryogenic calcite crystals
Cryogenic Calcite Crystals – loose grains of calcite found on cave floors, formed by segregation of solutes as water freezes.
[Omens]
Otherworldly Incantations Cave Worldbuilding dogtooth spar
Dogtooth Spar – large calcite crystals often found near seasonal pools.
[Omens]
Otherworldly Incantations Cave Worldbuilding Frostwork
Frostwork – needle-like growths of calcite or aragonite.
[Omens]
Otherworldly Incantations Cave Worldbuilding Moonmilk
Moonmilk – a white, creamy substance found inside limestone caves.
[Omens]

PART 9: SPELEOGENS & EXOTICS

Speleogens cave formations created by erosion via the removal of bedrock, rather than as secondary deposits. Can have various colorations from chemicals like iron oxide, copper, or manganese oxide, or sometimes brown from mud or silt.
Otherworldly Incantations Cave Worldbuilding Boneyard
Boneyard – an intricate maze of limestone with many holes, where material has dissolved away.
[Omens, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Boxwork
Boxwork – speleogens formed when bedrock between preexisting calcite veins weathers away preferentially during cave development.
[Omens]
Otherworldly Incantations Cave Worldbuilding Pillar
Pillars – speleogen columns formed by gradual erosion of softer rock like sandstone, rather than deposition.
[Omens]
Otherworldly Incantations Cave Worldbuilding Scallops
Scallops – small, asymmetrical, scoop-like depressions of variable size and reflective of longterm water flow patterns.
[Omens]
Exotics miscellaneous rare speleogen phenomena.
Otherworldly Incantations Cave Worldbuilding Calcite Rafts
Calcite Rafts thin accumulations of calcite that appear on cave pool surfaces.
[Omens]
Otherworldly Incantations Cave Worldbuilding Cave Pearls
Cave Pearls small “seed” crystals resulting from water dropping high above, forming near-perfect spheres of calcium carbonate.
[Omens]
Otherworldly Incantations Cave Worldbuilding Cave Popcorn
Cave Popcorn / Coralloids / Cave Coral small, knobby clusters of calcite, aragonite, or gypsum.
[Omens]
Otherworldly Incantations Cave Worldbuilding Hells Bells
Hells Bells – submerged, bell-like shapes.
[Omens]
Otherworldly Incantations Cave Worldbuilding Snotite
Snottites / Snoticles colonies of predominantly sulfur-oxidizing bacteria having the consistency of snot.
[Omens]

PART 10: PITS & SHAFTS

Otherworldly Incantations Cave Worldbuilding Abime
Abime / Pit Caves / Pot Caves / Shaft Cave / Jama – a vertical shaft in karst terrain, sometimes very deep, usually opening into a network of subterranean passages.
[Omens, Overlooks, Passageways, Abyss, Battlegrounds]
Otherworldly Incantations Coastal Worldbuilding Blowhole
Blowhole – a hole in a sea cliff or coastal terrace through which columns of spray jet upward loudly. Most likely to occur along fault lines or on islands, where waves concentrate and release in coastal rock crevices.
[Omens, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Cenote
Cenote – a natural pit or sinkhole that exposes groundwater underneath as limestone bedrock collapses. Culturally associated with locations for sacrificial offerings.
[Omens, Overlooks, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Foiba

Foiba an especially deep natural sinkhole comprised of a collapsed portion of bedrock above a void. Water erosion gradually excavates chasms into the shape of an inverted funnel.
[Omens, Overlooks, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Karst Fenster

Karst Fensteran unroofed portion of a cavern which reveals part of a subterranean river.
[Settlements, Omens, Overlooks, Passageways, Abyss]
Otherworldly Incantations Tundra Worldbuilding Moulin
Moulin / Glacier Mill – a roughly circular, vertical well-like shaft within a glacier or ice sheet which surface water enters.
[Omens, Overlooks, Passageways, Abyss, Battlegrounds]
Otherworldly Incantations Cave Worldbuilding Panhole
Panhole / Weathering Pans – a shallow depression or basin eroded into flat or gently sloping cohesive rock, sometimes found in deserts.
[Settlements, Omens, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Scowle
Scowlefeatures ranging from amorphous shallow pits to irregular labyrinthine hollows.
[Settlements, Omens, Passageways, Abyss]
Otherworldly Incantations Cave Worldbuilding Sinkhole
Sinkholea depression or hole in the ground caused by a surface collapsing into an existing void.
[Omens, Overlooks, Passageways, Abyss]

PART 11: SPECIAL CAVE FEATURES

Otherworldly Incantations Cave Worldbuilding Boulder Choke

Boulder Choke a collection of large rocks or rubble that obstructs the passage of a cave.
[Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Cave In

Cave In a partial or total collapse of a cave structure, potentially opening new passages or blocking old ones. Glacial formations prove extra susceptible.
[Omens, Passageways, Abyss, Battlegrounds]

Otherworldly Incantations Cave Worldbuilding Cave Window

Cave Window a hole in a thin wall that connects two chambers or passages, or that exposes the outside of the cave.
[Omens, Overlooks, Passageways]

Otherworldly Incantations Cave Worldbuilding Sunhole

Sunholes a hole in a cave roof which lets in sunlight and air.
[Omens, Overlooks, Passageways]

Otherworldly Incantations Cave Worldbuilding Underground Tunnel

Subterranean Tunnel in certain soil and rock conditions, underground tunnels can form which can function as passageways.
[Omens, Passageways, Abyss]

Otherworldly Incantations Cave Worldbuilding Underground Waterfall
Subterranean Waterfalla waterfall located underground, common where vertical drop-offs occur in caves.
[Omens, Overlooks, Passageways, Abyss]

FINAL THOUGHTS

I hope you enjoyed this twelfth entry in my Mythic Ecology series! I look forward to continuing with it, I have some greater ambitions for developing this series into worldbuilding web tools. Give this a share if you liked it, and let me know in the comments if you have any feedback. I publish new posts on alternating Tuesdays. In the meantime, I post original D&D memes and writing updates over on my site’s Facebook Page. Also, if you want to keep up-to-date on all my posts, check out my Newsletter Sign-Up to receive email notifications when I release new posts. A big thanks as always to my Patrons on Patreon, helping keep this project going: Adam, Alexander, Anthony, Benjamin, Chris, Eric & Jones, Evan, Geoff, Jason, Rudy, and Tom. Thanks for your support!

 

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Tril

D&D 5e blogger.

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