McElmo Phase refers to a period in the late 11th and early 12th centuries, when drastic changes in ceramics and masonry techniques in Chaco Canyon appeared, archeologists initially suggested that the McElmo influence was brought to Chaco Canyon by immigrants from which site located in Montezuma County, Colorado, it protects some of the best preserved Ancestral Puebloan archaeological sites in the United States?
McElmo Phase:  Archeologists initially suggested that the McElmo influence was brought to Chaco Canyon by immigrants from Mesa Verde, but subsequent research suggests that the developments were of local origin. Mesa Verde National Park: Mesa Verde National Park is a National Park and World Heritage Site located in Montezuma County, Colorado.
Mesa Verde National Park