Excursion Holocene 4 Paleomagnetism 4 magnetic reversal 4 natural remanent magnetization 4 paleomagnetism 4 Archaeology 2 California 2 Ecuador 2 Paleosecular variation 2 Pichincha 2 Pleistocene-Holocene boundary 2 Pleistocene-holocene transition 2 Red Rock 2 South America 2 United States 2 archaeology 2 geomagnetic field 2 magnetic intensity 2 remanent magnetization 2 secular variation 2 virtual geomagnetic pole 2