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
Salting the earth Salting the earth Salting the earth, or sowing with salt, is the ritual of spreading salt on conquered cities to symbolize a curse on their re-inhabitation. It originated as a symbolic practice in the ancient Near East and became a well-established folkloric motif in the Middle Ages. The custom of purifying or consecrating a destroyed city with salt and cursing anyone who dared to rebuild it was widespread in the ancient Near East, but historical accounts are unclear as to what the sowing of salt meant in that process. Various Hittite and Assyrian texts speak of ceremonially strewing salt, minerals,