Its upper portions are rich in olivine and comprise the asthenosphere.
The lowermost portion of this region has maintained its name from Keith Bullen's nomenclature; it is known as D double prime and is the likely source of the Gutenberg discontinuity.   Some of its notable features are formed by heat rising in diapirs and may create flood basalts, and the Morgan type of them is strongly influenced by a liquid layer beneath this. Its upper portions are rich in olivine and comprise the asthenosphere. For 10 points, name this layer of the earth that produces plumes, found below the Moho discontinuity from the crust.
The lowermost portion of this region has maintained its name from Keith Bullen's nomenclature; it is known as D double prime and is the likely source of the Gutenberg discontinuity.   
{mantle}