CrustThe crust is Earth’s thin, rocky skin. Oceanic crust is usually about 5–10 km thick; continental crust is commonly 30–70 km thick. Below it, the mantle begins at the Mohorovičić discontinuity.Earth’s interiorCrustUpper mantleLower mantleOuter coreInner coreInnermost inner core (IMIC)Beneath the seafloorNASA · Earth