The western part of the North Panama deformed belt (NPDB) undergoes a number of changes in the orientation of the frontal thrusts, in marked contrast to the eastern part of the NPDB, which shows very little change over distances of 150 km. In the western part of the belt, vergence and structural style of the frontal thrusts vary rapidly along the belt, again in contrast to the eastern part of the belt. The northeast-trending part of the western NPDB appears to be constrained in orientation by the slope of the Panama arc, which lies parallel to the thrust front. Farther...