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 is forming at least 52.6 million years ago; and the south side of Kōkō was date at 50.4 million years ago.