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.
Baseball card. A 1954 Bowman Gum baseball card of Vern Bickford. A baseball card is a type of trading card relating to baseball, usually printed on some type of paper stock or card stock. A card will usually feature one or more baseball players or other baseball-related sports figures.