A new model explaining this mysterious process suggests the core was created as dribs and drabs of iron percolated inward from Earth's lower mantle, according to a study published Oct. 6 in the journal Nature Geoscience. The mantle is the viscous, rocky layer between the crust and Earth's iron core.
Definition of flash card. : a card bearing words, numbers, or pictures that is briefly displayed (as by a teacher to a class) usually as a learning aid.
A stack of colored notecards. noun. The definition of a small firm sheet of paper used for writing a short message or for keeping small pieces of information. The lined cards used for presentation notes are an example of notecard.