Each Elemental Plane contains the primordial energy of that element enclosed in an infinite space 6.
In there is where the Pure Elemental Beings lives (beings composed only of the element in which they live) and also other Elemental Beings and multitude of Interplanar Beings 7a, such as Osselias 7b.
There are a lot of Elemental Planes, but the most known (although not the most relevant, I will explain that later) are the Elemental Planes of Fire, Earth, Water and Air, besides the Elemental Plane of Wood, Metal and the one known as Ethereal or Vacuum 8. There are also Elemental Planes of all the chemical elements, as well as many other materials (e.g. Vhäthrill 9: lloy of mithril, adamantium and celestial iron)
Other similar Planes, such as Color Planes are sometimes clasified as Elemental Planes, although are mostly Absurd Worlds 10.
In Milegu, generally, it is considered that the Elemental Planes of complex subtances are not mixes with other Planes, and even have the same power and rank. This imply that no Elemental Plane —either Mud Elemental Plane or Water Elemental Plane— is privilegied over others. There are not more import. There aren't any Elemental Plane more important than the others.
It also should be noted that "traditional" Elemental Planes are not fully "elemental" in the sense of being basic substances or not, but they are composed substances.
It can serve as an example the Elemental Plane of Air (as is a gas mixture) versus Elemental Plane Radon (noble gas that coincides with the notion of "elemental"). "Water" is a molecule composed of two different chemical elements (H2O), fire is a combustion and not even a substance and "earth" is a combination of different minerals.
In some Planes or contexts the Material Plane is seen like a Neuter Plane, the union of all Elemental in only one, the perfect mix of them (this is like that in the MDM of Ythjontar, but they consider a limited number of Planes).
It is also considered that when some of the Planes intersecting between them, form other Planes called Paraelemental Planes. One example of this would be the Quasielemental Planes of Ythjontar, formed by the union of Elemental Planes with the Energy Planes of Ythjontar. This kind of Planes don't have a lot of interes in Milegu, because in Milegu it is consider that each Elemental Plane cames by itself and not by mixing with anothers.
Also, the denomination "Energy Planes" it means different in Milegu.
However, in Milegu, the Material Planes aren't Neuter Planes nor Elemental Planes.
The Elemental Planes of Milegu rarely intersect between them (they can do it), firstly because they are situated at large distances and they can be placed in several places at once.
The Elemental Planes (of Milegu) behave as if they were Astral Planes of Species; i.e. house the Essences 11 of the creatures of that Element. The Elemental Planes are endless places where multitud of species and different forms of live arise.
Like in the Material Plane, the Elemental Planes are subdivided in different structures like Planes and Nested Planes 12.
But, so, the Elemental Planes (of Milegu) behave similar to the Dimensions of Milegu (in terms of structure)? Well, basically, yes. The Elemental Planes are a Dimension where there are a lot of Planes and diverse structures with different behaviours.
We do not have the specific names of all of those Planes because its inhabitans are not interested in these issues and very few beings have visited more than two or threee kinds of Elemental Planes that were of the same element. If they have done, they haven't aware of being visiting different Elemental Planes. Due to overwhelming similarity that the different Elemental Planes have between them, a lof ot the Interplanar Beings have failed to distinguish between the diverse levels of the Elemental Planes.
However, we know from the notes taken by the Sercque and found by Duusilt Dussians (image) that the Elemental Planes are composited of a series of Planes attached inside each other forming several levels.
Depending of the level (and isn't that depends from direction/depth/other variable, because the distances between the levels of the Elemental Planes are something abstractal and without real sense) the element itself is more or less present.
So, in the Elemental Plane of Fire —to which we should call it Elemental Dimension of Fire, but the naming convetion is still preferred to Planes— there are several levels.
To distinguish a single Elemental Plane from all the Elemental Plane (the Elemental Dimension) it is frequently used the terms: Parcial Elemental Plane and Total Elemental Plane. This distinction does not occur when speaking generically of Elemental Planes because they aren't studied by any other race than Sercque.
Levels of an Elemental Plane
As I said, the Total Elemental Planes have different levels and in all respects behave like Dimensions.
Each one of the levels have different magnitude or strenght of element itself. Ther are not sorted in any way and therefore we can't speak of an Elemental plane "superior" (the one that it has more presence of the element) nor an Elemental Plane "inferior" (that have less presence). It is referred, however, with how much strengh the element it appear in the Plane.
Partial elemental planes that are not sorted means that, if we take as reference two partial Elemental Planes are very "close", that does not mean they have similar temperatures and therefore also haven't a similar presence of the element.
To denote Partial Elemental Planes, the Sercque set a graduation technique based in an exotic alphabet called cxȱ’qre, used by the specie of the same name (image).
In the cxȱ’qre alphabet there are 40 letters that, besides serving as a pronunciation guide, correspond to a numerical value of base 41. And that also means the temperature scale according cxȱ’qre.
This plain system served the Sercque to numbering, naming, and classifying according their temperature (or according other variables appropiate to the other planes different to the Elemental Plane of Fire), the thousand of planes that find in their exploration. They only introduces little modifications in order to clarify the pronunciation and they included a parameter that allowed to extend the cxȱ’qre temperature scale as much as needed 13.
The Sercque marked the Partial Elemental Planes that visited 14 with ethereal marks, visible only by themselves. Those marks describing in whole each Elemental Plane allowing to identificate them by a unique name. There is speculation these brands were really Abstractions of Essences 15.
The differences between different Elemental Planes are radicals. In one extreme of the scale we have worlds as Ariano (air), Pryan (fire), Abarrach (piedra) and Chelestra (water) that baraly can be considered Elemental Planes as such and that fit rather in the worlds or planets with a lot of part of that element. The Elemental Planes similar to those ones are called Weak Elemental Planes.
There are "Elemental Planes", that aren't such, in where it coexist 4 or more elements in the same World or planet. Normally are of small size and those fractions battle against the others. This Planes are called Pseudoelemental Planes or Elemental Pseudoplanes because that, since they aren't separate between them it can't be considered planes or, seeing from another point of view, that represent an Element in particular.
Anyway there are voices of theoretical experts about Planes that disagree on this denomination.
In the other extreme we have Absolute Elemental Plnes that are Planes of infinite size in where there are only the element that names the Plane and where lives creatures composed of that element (although a few and of little inteligence).
The most of the Elemental Beings and Osselias comes from the "Halfway" Elemental Planes, with a great presence of their own element but they have also with other elements of other Elemental Planes.
It is not accident that the more common Elemental Planes (supposedly) are the "halfway", because it is practically imposible to access to the Absolute Elemental Planes.
For example: the Absolute Elemental Plane of the Earth is a block of ground and rock totally solid, without any chinck and that do not have air nor oxygen.
There are Elemental Planes of Earth that don't have any gas nor other material but instead have grottoes or caves. Other weaker Elemental Planes are more habitable by beings of Material Plane and even by beings from other Elemental Planes.
This example is applicable to all the Elemental Planes.
Sometimes, in a Parcial Elemental Plane, the amount of element in the Plane can vary and, according to the area of the Elemental Plane where it is accessed, it will appear to be an Absolute Elemental Plane or a Weak Elemental Plane.
Connectivity and dimensionality of the elemental planes
The Elemental Planes, like everything in the Milegu, do not respond to a unique pattern fixedly defined.
The Elemental Planes of Milegu can to be connected with a given plane (by Qruze, for example) and, at the same time, if you look at this Elemental Plane from another Plane would ensure that not only is not connected with the first Plane, but that would be impossible. These so strange connections are called as connections "is-don'texist" and are dependent deeply of the paradoxes.
This means that the Elemental Planes, like many other types of planar spaces, have a thing known as "complex dimensionality" (property defined, among other things by presenting exotic connections and connections "is-don't-exist).
They also have a property known as multilocation consisting that the same Elemental Plane can be found in many locations simultaneously.
*1: Milegu is the term that defines my own universe. But this universe is better definied as "the multiuniverse of the posibilities and imposibilities". So in Milegu exists All: the possible and the impossible in the form of universes, planes, dimensions, and complex structures. The conflicts between all of this are expressed in the formation of a lot of paradoxes.
*2: The concept of Planar Spaces it is very similar to the concept called "Planes of Existence" in several cosmologies like D&D and others fantasy rol games. An analysis of what it is a Plane (although it is something different than a Planar Space, because all the Planes are Planar Spaces but not all Planar Spaces are Planes) it can be read here → The Planes of Milegu.
*3: In Milegu cosmology, Dimensions are groups of Planes very similar. The Planes that are in the same Dimension are very close in abstractal terms and this proximity causes the similitude between those planes. The Dimensions don't have space by themselves, but it is the sum of the group of the spaces that have the Planes.
This concept it isn't similar to the astrological or pseudoscience concepts of "above dimensions" nor the scientifical concept (mathematical or physical) of dimension.
*4: A "Million of Worlds" (MOW) is a type of structure that belongs to Milegu cosmology. The term does not really describe what actually a MOW is because each MOW is actually composed by infinite members (or worlds). Simplifying, a MOW is a conection between worlds, planes, dimensions, universes, galaxies etc... that have some similarities. There is more structures like MOWs, and are called "Qadenas" [in english: Shains;
Qadenas is mistype of spanish "cadenas" (chains)]. Those Shains are conections between worlds that have something in common. A Shain not only includes the conection itself but also the planets. The main difference between normal Shains and MOW is that MOW are a bit disconected from the chaos that are Milegu (that chaos is produced by the confluence of impossibilities and possibilities (paradoxes)). Another point of difference is that MOW is a Shain of Shains where it can be mixed very different type of planar structures.
*5: Ythjontar (listen) is a MDM/MOW (in spanish Millón-de-mundos=Million of worlds) that have the D&D worlds: Krynn, Forgotten Realms, Planescape, Spelljammer and invented worlds of mine like Lyndon. So each time that you see Ythjontar in the text imagine a D&D universe.
*6: Although it is normal that the Elemental Planes are of infinite size, there are Elemental Planes of finite size and even Elemental Planes with very reduced size.
*7a, 7b: Interplanar Beings are those creatures who can stand in different Planes of their origin and can resist different types of Planes by their own means. Also it means those creatures that can survive in the Interplanar Fabric.
So, a Dussian can travel across the Interplanar Space and stay in other Planes (even harmfull), but they don't have that ability by themselves. Osselias are Elemental Beings that are independent from their Elemental Plane of origin.
*8: The "elements" that have reached us and which many "modern" cosmologies are based (that means, videogames, books, etc [like D&D, WOW, Death Gate Cycle...]), are constructed taking the greek conception of all that existed was composed of 4 mixed elements: the air, the fire, the earth and water. This way of describing the world through "elements" have also a parallel in civilizations as chinese or hindu, that add wood and metal (leaving the air) and the ethereal, respectively.
Here it have tried to gather all of those visions to make them a new shape.
In Greece also there was another conceptions about the composition of the things like: Eleatics , Atomism , Thales (water like Arche), Heraclitus (fire like origin of all things), Anaximenes of Miletus (air), Xenophanes (earth and water of the sea), and also theories that unified with the previous ones like those of the Empedocles (roots) and Anaxagoras (ὁμοιομέρεια/homeomerías(?) or seeds).
[Also a notice must be done. Although Greece was the "cradle of philosophy" after Socrates , before him, Greece was philosophically/science/mathematically very influenced by the asiatic powers. So, it will be fake to pretend that all of those innovations (also in mathematics, music, etc) just popped there. Of course Greece was very important later with the normalization of many things (formulation, innovation in philosophy), but normally there is underestimated the cultural input of non-Greek cultures to the science, mathematics and philosophy that finally reached us.]
This conception of the composition of things passed to christianism that grown it and strengthened and, with the rise of science (that proved false all previous systems except the atomistic, which corrected its faults), the four elements were relegated to the world of fantasy (although there are unscrupulous people who try to do business with it like other astrologers and bunch of charlatans).
So today, the 4 "elements" of Greeks have raised a great inspiration originating in fantastic environments, also they are frequently used by psychics charlatans and other riffraff (tarot readers, astrologers, and others that tease the intelligence) .
I wanted to add other elements from different civilizations to highlight the fact that formerly used for the purpose of finding relationships between these elements, usually following a very interesting philosophical basis (the Wu Xing, or five elements of Chinese philosophy ).
*9: The Vhätrill is a metal, alloy of celestial iron, mithril and adamantium that resists enormous temperatures and pressures. Is used by the Vhälatrill Scarabs.
*10: Absurd Worlds are strange spaces where inusual actions takes place in a repeated manner.
*11: Essences in Milegu are like metaphysical DNA of an specie or of an object.
*12: Nested Planes are Planes that are located insided of other Planes. They have different shapes and sizes but they have in common that they are anchored to a Plane.
*13: Therefore we only have to learn the alphabet cxȱ'qre and the parameter entered by the Sercque, to know, at the same time, the temperature of each of the Elemental Planes visited and their degree of presence their element.
*14: The Sercque visited all the Parcial Elemental Planes of all less exotic elements. An example of one Elemental Plane not visited for the Sercque were the Elemental Plane of Cobalt.
*15: The Abstractions of Essences are similar to the Textures of Essences 15b., because they are also Essences that have a physical shape. The difference between Textures of Essences and Abstractions is that Abstractions are a lot of Essences compressed in one.
*15b: The Textures of Essences are Essences that can be physically manipulated.