Geology

The world of TerraFirmaCraft is divided into large continents - landmasses many kilometers wide and seperated by oceans. In these, you may find mountain ranges, rivers, and many other environments.

Rock Layers

The world is also 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.

Ocean Floors

Ocean floors are composed of igneous extrusive rock - rocks that are formed by magma which cools quickly. Underneath igneous extrusive rock will likely be a igneous intrusive rock of the same grade.

For example, under Basalt (a mafic, igneous extrusive rock), will likely be Gabbro (a mafic, igneous intrusive rock).

Igneous Rock Grades

• Felsic rocks are Granite and Rhyolite.
• Intermediate rocks are Andesite, Dacite, and Diorite.
• Mafic rocks are Basalt and Gabbro.

The top layer of rock on a continent will either be igneous extrusive, or sedimentary. Underneath sedimentary rocks will likely be metamorphosed forms of the rock above.

For example, Marble (a metamorphic rock) will likely be found under Limestone or Chalk. High grade metamorphic rocks are found deep under other metamorphic or igneous rocks.

Metamorphic Rocks

• Slate forms under Shale, Claystone, and Conglomerate.
• Marble forms under Limestone, Dolomite, and Chalk.
• Quartzite forms under Chert.
• Phyllite forms under Slate
• Schist and Gneiss form under Phyllite, or other igneous intrusive rocks.

Uplift Regions

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,

protruding through the upper layers of rocks.

With all that in mind, the next few pages list the rocks of all four categories: Sedimentary, Metamorphic, Igneous Extrusive, and Igneous Intrusive. These categories determine where the rock can spawn (see the previous pages), and also what ores may spawn in this rock.

Sedimentary

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. They are:

• Shale
• Claystone
• Limestone
• Conglomerate
• Dolomite
• Chert
• Chalk

Metamorphic

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

• Quartzite
• Slate
• Phyllite
• Schist
• Gneiss
• Marble

Igneous Extrusive

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. They are:

• Rhyolite
• Basalt
• Andesite
• Dacite

Igneous Intrusive

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. They are:

• Granite
• Diorite
• Gabbro