OVERVIEW OF THE UNDERDARK


Natural Underground Locales
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Unnatural Underground Locales
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Hazards of the Underearth
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Dungeoneer's Survival Guide
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Although one type of underground environment might seem to be
pretty much like another, especially when a character cannot see
his nose in front of his face, a wide variety of locations await the
character willing to explore his surroundings and press on into
deeper and uncharted passageways.

The most significant && fundamental differences between
underground locations are due to their origins. Were they created
by natural geological forces such as erosion, earthquakes, or volcanic eruptions?
Or were they created by the efforts of creatures,
intelligent or unintelligent, to serve their needs?

The Rat God (god of underground areas)

Natural Underground Locales


Limestone Sea Lava Geothermal
Cave Formations Luthic (goddess of caves) Beltar (goddess of deep caves) Overview of the Underdark

Caves && caverns have been created by natural forces and
have appropriate characteristics. Often such locations serve as
starting points for dungeon settings.

Three types of caves are commonly encountered:
limestone caves,
sea caves, and
lava caves.

Limestone caves are by far the most common type. 


The Limestone Caverns (1 sq. = 10')

Obviously

they are mostly found in areas where the bedrock consists of a
great shelf of limestone. However, dolomite && marble terrain can
also serve as an environment for the creation of a limestone cave.

A limestone cave is created by the erosive and corrosive action
of water seeping through the rock. Rainwater in particular aids in
the creation of a limestone cave, since the carbon dioxide
absorbed from the air helps to make rainwater a dilute form of
H2CO3--a fluid that quickly eats away limestone.

As the water seeps through the earth, gradually widening its
passageways, the limestone cave grows. Shifts in the water
table, caused by drought, floods, or gradual movement of terrain
features, can increase or decrease the flow of water through the
cave. If the water table drops, formerly underwater passages are
left dry and full of air, creating a cave like those that have sheltered
creatures since the beginning of time.

Such caves can often be entered through the inlets or outlets of
the water that once flowed through them. Although often tortuously
narrow or steep, such openings are the most common
entrances to limestone caves.

A cave that grows too large may not be able to support the
expanse of rock above it, and the ceiling may collapse to form a
sinkhole. Such a feature drops precipitously from the surface to
the floor of the cave, but can be used as an entrance for characters
willing to do a little rope work. <(Rope & Wall: +40%)>

When the water has drained from a limestone cave, it is not
uncommon for seepage or even small streams to continue to
trickle through it. It is the seeping of small trickles of water that
creates many of the spectacular underground rock formations
that are familiar to those who have ventured into caves.

The most commonly known cave features are stony pillars
known as stalactites (hanging from the ceiling) and stalagmites (growing upward from the floor). As with other cave features, they
are created by the slow dripping of water, which evaporates and
leaves behind small deposits of minerals. Depending on the
types of minerals left behind, these cave features can range in
color from a muddy brown to red, or even (in rare cases) a pure
crystalline white.

Other types of cave features include draperies, flowstone, and gypsum flowers.

  • Draperies (also referred to as curtains) occur where evaporating water has left a sheet of stone that resembles a ruffled curtain.
  • Flowstone often falls in a series of tiers and resembles flowing sludge.
  • Gypsum flowers are rare and delicate little structures that can be extremely beautiful.

  •  

     
     
     
     
     
     
     
     
     
     
     

    If a cave is subject to continuing water seepage, it is considered
    a living cave, and these features are slowly growing
    throughout it. In fact, it is not unheard of for a cave’s features to
    grow so much that they literally fill in the cave that the same process
    (of dripping and running water) created in the first place.

    Features in a living cave glisten and shine when light is cast
    upon them. They are also very sturdy. Although occasional areas
    of rubble might obstruct passage, such caves are generally very
    clean and almost dust-free. Of course, this is before the cave is
    entered or used by creatures from the outside world or exposed
    to air from the surface.

    Mud is also a very common feature of a living cave. All low
    areas that are not regularly swept by flowing water contain pools
    of sticky mud. Depending on the drainage and shape of the area,
    these mud pools can be quite deep.

    A dead cave, on the other hand, is one in which the water no
    longer flows. The features in a dead cave do not glisten, and in
    fact grow very weak without the constant humidity to reinforce
    them. Left without water long enough, a cave’s features become
    very brittle and eventually crumble into dust.

    A dead cave is much more likely to be choked with rubble than
    its living counterpart. A layer of dust often covers everything. If
    water can be found, it has generally been standing in a pool for
    centuries. Even so, the water found in such locations is very
    rarely stagnant-the cold temperatures and lack of sunlight see
    to that.

    Some limestone caves are completely filled with water. These
    caves do not have the features described above, unless those
    features were created when the cave was filled with air, and it has
    subsequently filled with water. In general, the passages in a
    water-filled cave are smooth and rubble-free. Nonetheless, the
    water may flow through very narrow openings or tightly winding
    passages, making it difficult or impossible for a character to travel
    through.

    CAVE FORMATIONS


     

    STALACTITES
    http://www.anuvawines.com/tasting-argentina/wp-content/uploads/2013/01/Stalactites.jpg

    STALAGMITES
    http://scienceillustrated.com.au/blog/wp-content/uploads/2012/05/stalagmite.gif

    COLUMNS
    http://www.composedvolcano.com/wp/wp-content/uploads/2009/11/cave3.jpg

    DRAPERIES
    http://www.tpwd.state.tx.us/outdoor-learning/resources/keep-texas-wild/cave-creatures/images/drapery_1.jpg

    FLOWSTONE
    http://www.brazosport.edu/sites/CurrentStudents/Faculty/JoyKennedyOneill/My%20Caving/flowstone%20in%20Mexico.jpg

    GYPSUM FLOWERS
    http://www.saudicaves.com/larsgallery/23.jpg


    9.

    Sea caves are formed along current or former coastlines where
    the erosive action of pounding surf gradually wears an entrance
    into the bedrock.

    Taylor Blanchard - The Cave

    They are generally much smaller than limestone
    caves, since the waves disperse their energy quickly as
    they work their way inward.

    Sea caves are often partially water-filled. Depending on the
    changing level of the water, a sea cave might even be completely
    submerged, its mouth hidden to all observers who are not themselves
    submerged. On the other hand, if the water level has fallen
    or the ground has risen, a sea cave might be discovered in a cliff
    far above the pounding surf, or even many miles inland if the
    coast has gradually moved farther out to sea.

    Sea caves have smooth floors, walls, and ceilings, with none of
    the spectacular features of their limestone cousins. On the other
    hand, their often relatively easy access makes them more likely
    to contain some relic of long-past inhabitants.


    8.

    When a river flows around a bend, the abrasion of water
    against the outer riverbank might erode a space that eventually
    becomes fairly large. Such caverns resemble sea caves in most
    respects.

    Lava caves are created when the crust of a flowing surface of
    lava hardens, but the molten lava beneath the crust continues to
    flow.

    If the conditions are right, the lava flows away to leave an
    air-filled space that may reach a considerable size.

    Lava caves are commonly found in areas of volcanic activity.
    They do not contain the features typical of limestone caves.
    Unless the lava caves are in a region of heavy rainfall or are at a
    very low elevation, they may well be completely dry. In fact,
    because of their origins, a great many lava caves have no exits to
    the outside world. Their existence can only be discovered by
    chance excavation, or perhaps by accidentally breaking through
    the crust in an area where it is very thin.

    Earthquakes && rockslides can occasionally create underground
    chambers that are tenuously supported by accumulated
    rubble. While these underground locations resemble caves, they
    are not true caves. Occasionally such a chamber may be large
    enough for a party of characters to enter, but rarely is there much
    to see. These locations, however, can make good overnight shelters
    and may also provide comfortable lairs for any number of
    potentially hostile animals || monsters.

    Geological faulting can create cavities in the earth when a
    large shelf of rock moves and the neighboring rock remains stationary.
    Such caverns are often completely enclosed, but may be
    very large.


    <move this one to the appro. section, and link to that section from the above>

    Quote:
    Originally Posted by fett527
    Gary,

    If you fall in lava, do you get a saving throw?


    Yah, right! 


    1 or less of 10d10 saves.

    Gary
     

    Quote:
    Originally Posted by Holy Bovine
    If Gary Gygax falls in lava the lava doesn't get a saving throw.

    Everyone else just dies.


    This brings to mind the use of certain potent magical devices that would indeed pretty much negate the effects of lava or magma--anything having to do with compatibility with Elemental Fire.

    Having been divorced from my first wife, I no longer need such magical protection 

    Cheerio,
    Gary


    Geothermal heat is a feature that can be encountered in deep
    caves of any kind, although it is particularly likely in a lava cave,
    since the lava itself is a carrier of geothermal heat. Geothermal
    heat is simply heat energy originating from the unknown reaches
    deep under the crust of the earth.

    This heat can be encountered by underground explorers in a
    number of ways. The most dramatic, perhaps, is the glowing
    crimson flow of molten lava. Such melted rock carries heat from
    the deepest reaches of the earth toward the surface, and retains
    (and radiates) its heat for a long time. Molten lava has a temperature
    of approximately 1,800° F, and quickly kills any non-fire
    resistant creature forced to come into contact with it.

    Even in areas where the lava has cooled to a solid crust, it can
    still be blisteringly hot. A character foolish enough to venture onto
    such a crust runs the risk of breaking through into the infernal
    heat below.

    Steam is another manifestation of geothermal heat that could
    be encountered by cave explorers. Although not nearly as hot as
    lava, steam can nonetheless scald or even kill a creature caught
    in its intense blast. Steam can arise suddenly in areas of high
    geothermal activity, whenever water happens to run into some
    area that is hot enough to quickly vaporize it. Such instant vaporization
    can create high steam pressures, and cause blasts of
    steam to erupt far from the actual source of the heat.

    A more tolerable instance of geothermal heat is in the form of
    warm or hot water. Depending on the proximity and intensity of
    the heat source, the water temperature can range from lukewarm
    to boiling.

    Warm or hot air rising through subterranean passages can
    often be an explorer’s first warning that he is approaching a
    source of geothermal heat. This can actually be a pleasant experience,
    especially for characters well-chilled by a long expedition
    through dark and dank chambers.

    Unnatural- Underground Locales


     
    Dungeons Mines Burrows Realms

    Dungeons

    are familiar to nearly all adventurers.
    Some dungeons are constructed entirely from caves,
    while others use caves as entrances || emergency exits only.
    In any case, intelligent creatures

    The First Dungeon Adventure (DMG)


    10.

    have built each dungeon to serve a particular purpose.


     

    Dungeon passages generally run within a few hundred feet of
    the surface, although this is not a hard && FAST rule. The deeper
    the dungeon, however, the harder the task of moving the excavated
    {material} out of the way.

    Dungeons are generally excavated from a soft rock such as
    sandstone || limestone. These materials are not as hard to excavate
    as granite, for instance, and still provide a solid and sturdy
    support for the dungeon’s corridors && rooms. Some dungeons
    are excavated from dirt, and require constant shoring up (at least
    at 10-foot intervals) in order to prevent cave-ins. A dungeon excavated
    from dirt will not last as long as a stone dungeon.

    Some dungeons begin as buildings whose ruins are later buried
    by new buildings, until the original layer seems to be well
    underground. Dungeons can be encountered long after their construction,
    and may in fact be well on the way toward collapse--or
    they may be newly excavated or even in the process of construction when characters encounter them. <also, make a link to mining>

    Dungeons are created for a wide variety of purposes.
    The most common include service as jails, hiding places for treasures, lairs
    for bands of underground creatures, or positions of defense. In a
    world where flying creatures are ever-present, dungeons can
    prove to be stronger fortresses than castles!

    Mines in a fantasy world are almost always tunnels || shafts.

    Some mines, particularly those developed over many centuries
    by diligent excavators such as dwarves || gnomes, can become
    complicated networks of tunnels extending through three dimensions
    and stretching for dozens of miles.

    Mines can be either active or inactive, which indicates whether
    or not they are currently in use. The miners who created an inactive
    mine might have ceased their work because the vein of material
    they were excavating was depleted, but this is not necessarily
    so. Disasters or conflicts might have forced the operation to discontinue.
    Active mines are usually well-guarded, and inactive
    mines often become the lairs of subterranean monsters.

    Burrows are generally long tunnels, perhaps with a widened
    spot at some point, created by creatures as shelters.

    Only
    very large burrows are big enough for characters to enter; unfortunately,
    very large burrows are usually created by
    very large creatures that do not always react kindly to the intrusion.

    Burrows are generally excavated from dirt, but certain creatures
    (such as umber hulks) can create burrows in solid stone. A
    burrow is generally no bigger in diameter than the creature who
    created it, although a larger chamber is often excavated at the
    burrow’s deepest end.

    Realms are vast underground reaches made up of caverns,
    dungeons, and lofty passages of questionable origin deep
    beneath the earth.

    Realms are rarely found within a mile of the
    surface and often extend far deeper than this.

    These realms are regions of mystery to most surface-dwelling
    creatures. Information about them is based on speculation or the
    few first-hand accounts of adventurers who have visited these
    underground realms and returned to tell the tale.

    It is known that certain races, such as the drow elves, deep
    gnomes, duergar, kuo-toa, and derro, to name a few, live in vast
    underground reaches that never see the light of day. The true
    extent of such realms can only be guessed at.

    These realms contain vast networks of caverns that might rival
    an entire nation in size, and underground bodies of water as big
    as any outerworld sea. These seas contain islands just as surface



    11.

    seas do. Certain of the vast realms could best be described as
    wilderness, for no cultures flourish there, while other areas boast
    cities and fortresses worthy of the most ADVANCED civilizations.

    Many of the creatures inhabiting these realms have been
    encountered by surface dwellers in the meeting--ground of the
    dungeon, for this is where the deep--dwellers and surface dwellers
    are most likely to encounter each other. Other creatures--horrific
    beasts that never even venture up to the level of the
    dungeons--are rumored to live in these underground realms, but ,
    no one living can attest to their existence.

    Hazards of the Underearth
     
    Cave-ins Floods Fires Poisonous Gases Volcanoes


    -
    Dungeons, burrows, caves, and realms all share some com-
    mon hazards that are created by their location under the surface
    of the earth. The following dangers are relatively rare, but each of
    them can be life-threatening to a character deep below the surface
    of the world.

    Cave-ins are a constant problem to creatures living underneath
    tons of earth and rock. Cave-ins can be triggered by erosion,
    or by sudden shocks such as earthquakes or explosions.

    Of course, characters or creatures directly underneath a section
    of dungeon or cave that caves in suffer damage from the
    material falling on them, and are often pinned by the weight of
    this material, or trapped in a small area with little air.

    Dungeons are often protected against cave-ins by shoring up
    the passages with timbers or stone arches. Caverns do not have
    the benefit of such engineered protection, and realms are generally
    too vast for such protection to be practical. Because of their
    vast size and durability, the realms of the underearth are rarely
    subject to cave-ins. If a cave-in occurs in a realm, however, its
    potential for disaster rivals that of the worst hurricane or tidal
    wave ever to ravage a surface land.

    Floods are yet another natural phenomenon with potentially
    disastrous results. Because of the cramped nature of underground
    environments, flood water has little chance to spread out
    and disperse its effects. Indeed, underground corridors may well
    fill with water, making drowning a virtual certainty for any airbreathing
    creature caught there.

    Fires threaten the well-being of underground dwellings in a
    double sense, for they consume combustible objects in their
    path, and also use up the precious oxygen that definitely exists in
    a finite supply.

    Fortunately, at least for fire prevention, wood is not a very common
    building material underground. The difficulty of transporting
    wood into a dungeon and its tendency to rot in damp conditions
    both serve to discourage its use. Certain tasks, however, such as
    the shoring up of a corridor, are much more easily accomplished
    with wood than with stone.

    Poisonous Gases present an unseen but real menace to all
    creatures that must rely on oxygen for life. These gases can be of
    natural origin, such as the sulfur dioxide commonly created
    around areas of volcanic activity, or can be of magical or manufactured
    origin. Obviously, the use of poison gas as a weapon of
    war is greatly enhanced in the constricted conditions of the
    u nderearth.

    Volcanoes are a major cause of subterranean fires and poisonous
    gas emissions, as well as other problems. Often occurring in
    conjunction with earthquakes, a volcanic burst can fill inhabited
    corridors with lava or steam, or close off escape passages or popular
    transportation routes.


    12.