syncline
noun /ˈsɪŋklaɪn/
/ˈsɪŋklaɪn/
(geology)- an area of ground where layers of rock in the earth’s surface have been folded into a curve that is lower in the middle than at the ends compare anticlineWord Originlate 19th cent.: from syn- ‘together’ + Greek klinein ‘to lean’, on the pattern of incline.