Definition: A depressed block of land bordered by parallel faults. A graben is the result of a block of land being downthrown producing a valley with a distinct scarp on each side. Grabens often occur side-by-side with horsts. Horst and graben structures are indicative of tensional forces and crustal stretching.
Definition: The organization of the system of organs involved with sexual reproduction, e.g., hermaphroditism, monoecy, dioecy/gonochory, gynodioecy, androdioecy, gynomonoecy, andromonoecy, polygamodioecy, polygamomonoecy, apomixis, etc.