https://www.britannica.com/science/isostasy-geology
http://www.livescience.com/6595-depth-himalayan-mountain-ro?fbclid=IwAR2oNMekw9-Bcmh0mLvZOvaugLXmNChGcsVRtIL_YupBdEusCvofzJRclCE
http://www.livescience.com/37706-what-is-plate-tectonics.ht?fbclid=IwAR3EgiNutnv6v0NNOY2nMg4fglKOt_iisAxNCGE9TpK9UrEiydukf2OTbY8