(Solved): Above is a geologic map of deformed strata intruded by younger igneous rocks. The age and names of e ...

Above is a geologic map of deformed strata intruded by younger igneous rocks. The age and names of each of the igneous & sedimentary formations are given in the legend below the map. According to the map, certain geologic formations are structurally deformed such that there is repetition of sedimentary layers (i.e., there are two Dn layers and two Db layers) with the oldest layers occupying the center of the structure. What type of structure can cause this type of geologic feature?