crustal

adj

Etymology: Etymology tree English crust Proto-Indo-European *h₂el-der.? Proto-Italic *-ālis Latin -ālisbor. Old French -albor. ▲ Latin -ālis Old French -elbor. ▲ Latin -ālisbor. Middle English -al English -al English crustal From crust + -al.

1. Of, pertaining to, or forming a crust, especially the crust of the Earth or other planet.

   “The hope was to lower a drill through over 4,000 metres of Pacific Ocean water off the coast of Mexico and drill some 5,000 metres through relatively thin crustal rock.”