Concentric Ridges in Synclines Small 320×82 Medium 640×165 Large 1024×264 Download TIFF Original 2400×618 | (546.4 KB) Description Development of concentric ridges in synclines. A) a region with synclinal or canoe-shaped folds. B) The synclinal valley shown in A is replaced by a mountain because of the occurrence of a hard stratum in the center. Keywords concentric circle, syncline Galleries Structural Geology Source: Amadeus W. Grabau A Textbook of Geology (Boston: D.C. Heath & Co., 1920) 598