Earth Geology

The world of TerraFirmaGreg is divided into large continents - landmasses many kilometers wide and seperated by oceans. In these, you may find mountain ranges, rivers, and many other formations. Here you will learn about the geology of Earth and how rock layers are determined.

• Rock Layers
• Metamorphism
• Ocean Floors
• Uplift Regions
• Rock Devisions
• Sedimentary
• Metamorphic
• Igneous Extrusive
• Igneous Intrusive
• Rock Classifiers
• Sedimentary-Carbonate
• Sedimentary-Clastic
• Sedimentary-Organic
• Igneous-Felsic
• Igneous-Intermediate
• Igneous-Mafic
• Igneous-ultramafic

岩層

The world is divided up into different types of Rock. Rock regions can be over a kilometer across, and there will usually be two or three different rock layers under your feet at all times. As different ores are found in different rock types, locating specific rock types can be very important for finding resources such as Ores, which will often only appear in certain rock types.

大陸の最上層の岩は火成噴出岩または堆積岩のいずれかになります。堆積岩の下には、その上にある岩石の変成形態が存在する可能性が高いです。例えば、大理石(変成岩)は、石灰岩や白亜の下に見られることがよくあります。高品位の変成岩は、他の変成岩や火成岩の地下深くに見つかります。

Metamorphism

• 粘板岩は頁岩、粘土岩、および礫岩の下に形成されます。
• 大理石は石灰岩、苦灰岩、および白亜の下に形成されます。
• 珪岩は角岩の下に形成されます。
• 千枚岩は粘板岩の下に形成されます。
• 片岩と片麻岩は千枚岩、または他の火成貫入岩の下に形成されます。

海底

海底は火成噴出岩で構成されています。火成噴出岩はマグマが急速に冷却されることで形成されます。火成噴出岩の下には、同じ品位の火成貫入岩が存在する可能性があります。例えば、玄武岩(苦鉄質/火成噴出岩)の下には、斑れい岩(苦鉄質/火成貫入岩)が存在する可能性があります。

隆起地域

Finally, in mountainous regions you might also see uplift, where a metamorphic or igneous intrusive rock is found on the surface. Uplift rocks can be found above other continental sedimentary or higher-grade metamorphic rocks.

In addition, Dikes↪ - small vertical slices of igneous intrusive rock - may appear scattered around the world.

Rock Devisions

Rocks in TFG are typically classified among four devisions: Sedimentary, Metamorphic, Igneous Extrusive, and Igneous Intrusive. These categories determine where the rock can spawn, and also what ores may spawn in this rock.

Sedimentary↪ rocks are formed by the accumulation or deposition of mineral or organic particles. They are typically found on the top layers of rock in continental areas.

Metamorphic↪ rocks are created by a process called metamorphism. They can be found underneath corresponding sedimentary or igneous rock, or in uplift areas.

Igneous Extrusive↪ rocks are formed from magma cooling on the Earth's surface. They can be found on the top layer of rock in continental areas, or on the floor of oceans.

Igneous Intrusive↪ rocks are formed from magma which cooled under the Earth's crust. They can be found deep underground, or rarely in dikes or uplift areas.

Rock Classifiers

On top of Rock Devisions, rocks are further categorized by their chemical compositions.

Sedimentary-Carbonate↪ rocks are composed primarily of carbonate minerals like calcite.

Sedimentary-Clastic↪ rocks are composed of fragmants (clasts) of pre-existing minerals or rocks.

Sedimentary-Organic↪ rocks are formed from the breakdown or fossilization of organic matter like shells or bacteria.

Igneous-Felsic↪ rocks contain a rich presence of elements that form feldspar and quartz. Generally a rock must contain more than 75% of felsic minerals to be classified as Felsic.

Igneous-Intermediate↪ rocks contain 51.5 - 63.0 wt% SiO₂, putting them in between Felsic and Mafic compositions.

Igneous-Mafic↪ rocks contain a rich presence of magnesium and iron minerals.

Igneous-Ultramafic↪ rocks contain a very low concentration of silica.