marine isotope stages
... that there have been only 22 marine isotope stages in the last million years?
... that there have been only 22 <b id="mwB0U"><a class="mw-redirect" href="./Marine_isotope_stage" id="mwB0Y" rel="mw:WikiLink" title="Marine isotope stage">marine isotope stages</a></b> in the last million years?