The lowermost mantlelayer is above the core mantle boundary (CMB) and composed of D" region and ultra-low velocity zone (ULVZ)."
地幔底层由具有高地震波速和高密度的D″区和超低速带（ULVZ）组成。
2
Surprisingly, precious metals instead appear relatively abundant on the planet's surface and in the underlying mantlelayer. [Infographic: Tallest Mountain to Deepest Ocean Trench].
令人惊讶的是，在地球表面和下面的地幔层里贵金属反而比较丰富。
3
All are slowly moving because the plates float on a denser sem-iliquid mantle, the layer between the crust and Earth's core.