Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

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.
Science