fossil echinoids
... that fossil echinoids can be used to date the various chalk strata of the White Cliffs of Dover?
... that <b id="mwBL8"><a href="./Fossil_echinoids" id="mwBMA" rel="mw:WikiLink" title="Fossil echinoids">fossil echinoids</a></b> <i id="mwBME">(example pictured)</i> <a href="./Biostratigraphy" id="mwBMI" rel="mw:WikiLink" title="Biostratigraphy">can be used to date</a> the various chalk strata of the <a href="./White_Cliffs_of_Dover" id="mwBMM" rel="mw:WikiLink" title="White Cliffs of Dover">White Cliffs of Dover</a>?