“Ninety-nine and nine-tenths of the earth’s volume must forever remain invisible and untouchable. Because more than 97 per cent of it is too hot to crystallize, its body is extremely weak. The crust, being so thin, must bend, if, over wide areas, it becomes loaded with glacial ice, ocean water or deposits of sand and mud. It must bend in the opposite sense if widely extended loads of such material be removed. This accounts for … the origin of chains of high mountains … and the rise of lava to the earth’s surface.”
![“Mountains have been formed by one [or other] of the causes of the formation of stone, most probably from agglutinative clay which slowly dried and petrified during ages of which we have no record. It seems likely that this habitable world was in former days uninhabitable and, indeed, submerged…” quote by Avicenna](https://sms4smile.com/quotes/img-quotes/4ce/avicenna-19211_age_mountains-have-been-formed-by-one-or-oth_1402208.jpg)
![“[T]here are depths of thousands of miles which are hidden from our inquiry. The only tidings we have from those unfathomable regions are by means of volcanoes, those burning mountains that seem to discharge their materials from the lowest abysses of the earth.” quote by Oliver Goldsmith](https://sms4smile.com/quotes/img-quotes/b7d/oliver-goldsmith-772_abyss_t-here-are-depths-of-thousands-of-miles_88121.jpg)
