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Cretaceous period

(Encyclopedia)Cretaceous period krĭtāˈshəs [key], third and last period of the Mesozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), lasting from approximately 144 to 65 millio...

Jurassic period

(Encyclopedia)Jurassic period jərăsˈĭk [key] [from the Jura Mts.], second period of the Mesozoic era of geologic time, lasting from 213 to 144 million years ago. At the start of the Jurassic most of the contine...

Devonian period

(Encyclopedia)Devonian period dĭvōˈnēən [key], fourth period of the Paleozoic era of geologic time between 408 and 360 million years ago (see Geologic Timescale, tablegeologic timescale, table). It was named (...

Neolithic period

(Encyclopedia)Neolithic period or New Stone Age. The term neolithic is used, especially in archaeology and anthropology, to designate a stage of cultural evolution or technological development characterized by the ...

Mississippian period

(Encyclopedia)Mississippian period: see Carboniferous period. ...

Mesolithic period

(Encyclopedia)Mesolithic period mĕzˌəlĭthˈĭk [key] or Middle Stone Age, period in human development between the end of the Paleolithic period and the beginning of the Neolithic period. It began with the end o...

Paleolithic period

(Encyclopedia)Paleolithic period pāˌlēəlĭthˈĭk, –lēō–, pălˌ– [key] or Old Stone Age, the earliest period of human development and the longest phase of mankind's history. It is approximately coexten...

Pennsylvanian period

(Encyclopedia)Pennsylvanian period: see Carboniferous period. ...

synodic period

(Encyclopedia)synodic period sĭnŏdˈĭk [key], in astronomy, length of time during which a body in the solar system makes one orbit of the sun relative to the earth, i.e., returns to the same elongation. Because ...

Tertiary period

(Encyclopedia)Tertiary period tûrˈshēĕrˌē [key], name for the major portion of the Cenozoic era, the most recent of the geologic eras (see Geologic Timescale, tablegeologic timescale, table) from around 26 to...