Editing v0.34:Stone layers

{{Quality|Exceptional|18:30, 8 November 2010 (UTC)}}
{{av}}

There are four types of '''stone layers''' in Dwarf Fortress, very much based on real life geology. [[Stone]] layers are roughly homogeneous layers of rock that are composed of the same kind of stone, and usually contain different ores. Each stone layer has its distinct markers and qualities; sometimes a clear dividing line can be drawn between two [[biome]]s from the stone layers underneath, sometimes not. Digging deeper or digging into another local biome will reveal differences between contents and a progression from sedimentary down to igneous.

These changes are usually quite sharp; fifteen layers may be mostly [[quartzite]], but the next thirty layers may be dominated by [[gabbro]]. Three dimensional variance is planned for the future, but for now, changes between stone layers also mark changes in [[ore]] and [[gem]] content.

== Soil ==
{{main|Soil}}
Most maps have one or a few layers of [[soil]] at the very top, although this layer may be completely non-existent or ten or more layers deep as well. Note that on mountainous terrain, soil tends to accumulate near edges; thus you can have partial soil "layers" down the side of the mountain for quite a few z-levels.

Soil is important for three reasons: it is easily [[farming|farmed]] (not requiring [[irrigation]] like stone does), it is easily [[miner|mined]] (taking less time than stone), and it does not leave any loose [[stone]] behind when mined. Soil layers can contain [[clay]] and [[sand]], if your biome has any, as well as a high chance of being an [[aquifer]], if your biome has one. Soil layers do not contain ores or gems. At least one layer of soil is necessary to easily establish farming. It is ''not'' recommended you establish your main fortress in soil, as it cannot be [[smoothing|smoothed]] or [[engraving|engraved]] to make it visually appealing/more valuable.

== Sedimentary ==
{{main|Sedimentary layer}}
The [[sedimentary layer]] is the first stone layer that appears after any soil. It will include any [[lignite]] or [[bituminous coal]], if you are lucky enough to have some. [[Iron]] [[ore]] and all but one of the [[flux]]es is common here as well, making the sedimentary layer make-or-break for [[steel]] production. Note that this layer and the igneous extrusive are mutually exclusive, and will never be found in one place. Sedimentary layers are generally where the bulwark of the fortress will find itself, will contain most of the ores marked on the [[embark]] screen as "shallow metals", and is a good choice for [[exploratory mining]]. Note, however, that it is poor in [[gem]] content - those found in sedimentary layers are generally less valuable than those further down. Some types of sedimentary rock may contain an aquifer.

== Igneous extrusive ==
{{main|Igneous extrusive layer}}

In certain regions, igneous extrusive layers replace the sedimentary layers, but when present are not limited to the top-most layers and can appear anywhere except the bottom-most layer. Although being made of different rocks, they are similar to sedimentary layers, with the exception being that they often indicate the presence of [[magma]] above the [[magma sea]] itself. This is always the top-most layer near [[volcano]]es; the biggest stumbling block is that its presence means that the biome rarely contains any flux.

== Metamorphic ==
{{main|Metamorphic layer}}

Contains a small variety of [[vein]] ores, as well as [[marble]], the one non-sedimentary flux. Metamorphic layers generally contain moderately valuable gems, and if the sedimentary layer (or and especially igneous extrusive layer) above contains no flux stone, it is a useful early target for exploration in the hopes of finding flux. It does lack weapon-quality [[ore]]s (containing only [[copper]] and [[silver]]).

== Igneous intrusive ==
{{main|Igneous intrusive layer}}

Igneous intrusive layers can appear at any level except the top-most or above any sedimentary, and the deepest and often the thickest layer will always be igneous intrusive, just above the [[magma]] sea or [[semi-molten rock]]. Gems here are generally the most valuable, on average, with the most valuable of them all, colored diamonds, found in [[kimberlite]] in [[gabbro]] layers.

{{Category|Stone Layers|*}}