sentence: The north side of Kōkō Seamount was formed at least 52.6 million years ago; and the south side of Kōkō is dated at 50.4 million years ago.
modified: fix grammar: The north side of Kōkō Seamount was formed at lesser 52.6 million years ago; and the south side of Kōkō is dated at 50.4 million years ago.