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strewnfield An area which is associated with a specific group of tektites and microtektites that can be distinguished according to their age and chemical composition, and which probably represents a particular impact event. Four major strewnfields are known: the Australasian (formed 0.7 Ma ago), which is the largest and covers an area of about 5 × 107km2 around Australia and South-east Asia; the Ivory Coast (formed 1.3 Ma ago) covering an area at least 4 × 106 km2 around and off the coast of W. Africa; the Czechoslovakian (formed 14 Ma ago) without proven associated microtektites as yet; and the N. American strewnfield (formed 34 Ma ago) forming a belt stretching across the Pacific from South-east Asia to the western Atlantic, and of unknown latitudinal extent.