Earth's Crust
noun, の adjective
The earth's shell is called the earth's crust. You should have learned that in earth science. And if you didn't, at least you know now!
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
日本列島は、千年に一度の大地殻変動期に突入しています
The Japanese archipelago is entering a once-in-a-millennium period of significant tectonic upheaval.