The older Nemo calderas appear to predate the last glaciation, while the younger one is post-glacial in age. Nemo I formed 40,000 - 45,000 years ago and Nemo III 25,000 - 24,500 or 26,000 years ago; a radiocarbon date of 24,500 ± 740 years ago has been obtained on it. Nemo Peak proper formed about 9,050 ± 100 or 9,130 ± 140 radiocarbon years ago.