The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian periods respectively.. 
Lẹ́yìn èyí, òṣèlú kan láti orílẹ̀ èdè Sierra Leone jẹ́rìí pé omi mímọ́ náà ṣe ìwòsàn fún ọpọlọpọ àwọn tí àrùn náà ń bá jà, ti sìn dẹ́kun ìtànkálẹ̀ àrùn náà lórílẹ̀ èdè náà.Àwọn ìtọ́ka sí.. 