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Cambrian period

(Encyclopedia)Cambrian period [Lat. Cambria=Wales], first period of the Paleozoic geologic era (see Geologic Timescale, tablegeologic timescale, table) extending from approximately 570 to 505 million years ago. It ...

Ordovician period

(Encyclopedia)Ordovician period ôrdəvĭshˈən [key] [from the Ordovices, ancient tribe of N Wales], second period of the Paleozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table) fr...

Cambrian Mountains

(Encyclopedia)Cambrian Mountains kămˈbrēən [key], rugged upland plateau occupying most of Wales; Aran Fawddwy (2,970 ft/905 m) is the highest point in the mountains. The area has deep lakes and is cut by numero...

Cretaceous period

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

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 (...

Carboniferous period

(Encyclopedia)Carboniferous period kärbənĭfˈərəs, fifth period of the Paleozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), from 350 to 290 million years ago. The plant li...

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...

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 ...

Quaternary period

(Encyclopedia)Quaternary period kwətûrˈnərē [key], younger of the two geologic periods of the Cenozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table) from 2 millon years ago to t...

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