* 4 million years -- time since beginning of last Ice Age * 5 million years -- time since beginning of Pliocene Epoch * 5 million years -- time since end of Miocene |
* 4.0 million years -- time since beginning of last Ice Age * 4.2 million years -- half-life of Technetium * 5.0 million years -- time since beginning of Pliocene Epoch * 5.0 million years -- time since end of Miocene |