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.
Playing card. Playing cards is the name for the 54 cards used card games like poker, bridge, blackjack, and solitaire. There are 52 basic cards in a deck. These cards have a suit and a number (called the value or rank). There are 4 suits and 13 ranks in each suit. There are also two Jokers that do not have a suit or a rank.