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.
Flashcard definition, a card having words, numerals, or pictures on it, designed for gaining a rapid response from pupils when held up briefly by a teacher, used especially in reading, arithmetic, or vocabulary drills. See more.