move apart in plane of blatant impossibility

What does the phrase 'move apart in planes' mean?
'The glittering sea rose upmoved apart in planes of blatant impossibility; the coral reef and the fewstunted palms that clung to the more elevated parts would float up into the skywould quiverbe plucked apartrun like raindrops on a wire or be repeated as in an odd succession of mirrors.'

The sentence above comes from William Golding's book 'Lord of the flies'.

This is highly figurative language. It sounds like the sights imagined by someone in a feverish delirium.
'Moved apart in planes of blatant impossibility' means that the sea separated into different planes - levelsor surfaces - in a way that was obviously impossible.

Thank you.