Crust (geology) depth, reaching values typically in the range from about to at the boundary with the underlying mantle. The temperature increases by as much as for every kilometer locally in the upper part of the crust, but the geothermal gradient is smaller in deeper crust. The continental crust has an average composition similar to that of andesite. The most abundant minerals in Earth's continental crust are feldspars, which make up about 41% of the crust by weight, followed by quartz at 12%, and pyroxenes at 11%. Continental crust is enriched in incompatible elements compared to the basaltic ocean crust and much
Tales from the Flat Earth of agate, the second is made of blue steel, and the third gate is made of black fire. There is only one city in the Underearth – Druhim Vanashta, the city of demons. It is made of precious minerals, gems, and metals and is beautiful, though its inhabitants are cruel and wicked. The Flat Earth appears to include temperate, sub-tropical, and tropical zones, including many deserts. Since "polar" regions would be impossible on a flat world, they are not mentioned in the series. There are many seas, but bodies of water large enough to be called "oceans" do not appear