WHY IS BIRCH CREEK PLUTON UNIQUE?
Birch Creek pluton offers one of the clearest demonstrations of forcible emplacement of any of the plutons I have ever worked on or visited in field trips. That demonstration is clearly evident from the geologic map that shows the damage done to the internal structure of the White Mountain anticline by the pluton. The axis of the anticline trends and plunges south. It contains several subsidiary folds that also originally trended south, and the fold contains several steep-dipping N-S striking faults. The faults, folds, and fold axes were forcibly shoved west and northwestward by the pluton during its intrusion. Wyman and Reed formation strata were also overturned by the pluton as it shoved west, as can be seen clearly in the field from geopetal structures in the Reed Formation and by the attitudes of strata when followed around the north and west sides of the pluton from upright attitudes, to overturned attitudes, and then around a synformal anticline back to upright attitudes on the w
