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A usually elongate, basinlike depression along the edge of a continent, in which a thick sequence of sediments and volcanic deposits has accumulated.
ge′o·syn·cli′nal (-sĭn-klĭ′nəl) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.