Other eruptions identified through tephra at Lago Shaman and Mallín El Embudo occurred 4,800 - 4,600 calibrated radiocarbon years ago, while a late glacial maximum eruption over 19,670 years before present produced another thick tephra layer in the Río Cisnes valley. Two additional tephra layers, 8,300 and 19,700 years old, at Río Cisnes may also have originated at Melimoyu. Glacial activity has otherwise removed much of the record of volcanic activity before the post-glacial.