Grouse Creek block
... that the 2.5 billion year old Grouse Creek block forms part of the basement of North America?
... that the 2.5 billion year old <b id="mwCpI"><a href="./Grouse_Creek_block" id="mwCpM" rel="mw:WikiLink" title="Grouse Creek block">Grouse Creek block</a></b> forms part of the basement of North America?