ordovician Definition

ordovician period, conodonts, paleozoic, eocene, triassic, miocene, proterozoic, devonian, paleocene, paleogene, palaeozoic, oligocene, pliocene, precambrian, silurian, neogene, mesozoic, basalts, limestones, archaean, dolomites, turonian, palaeocene, cretaceous, phanerozoic, cenozoic, campanian, archean, diabase, graben, depositional, tertiary period, sedimentary, hornblende, gneiss, craton, brachiopods, pleistocene, lavas, stratigraphy, embayment, syenite, andesite, zechstein, cretaceous period, permian period, glaciation, gabbro, jurassic period, clastic, eocene epoch, metamorphism, schists, supercontinent, upper carboniferous, orogenic, huronian, shales, diorite, cambrian period, volcanism, alkalic, deglaciation, evaporite, rifting, syncline, hornfels, triassic period, mesozoic era, magmas, sediments, faunas, noachian, anorthosite, facies, granodiorite, amphibolite, stratiform, devonian period, interglacial, cenozoic era, batholith, ankerite, anticlines, granites, upper paleolithic, peridotite, igneous, relict, trilobites, siltstone, geochronology, phyllosilicate, lamprophyre, dolerite, unconformity, dacite, gondwanaland, neocomian, carbonate,