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Precambrian

(Encyclopedia)Precambrian, name of a major division of geologic time (see Geologic Timescale, tablegeologic timescale, table), from c.5 billion to 570 million years ago. It is now usually divided into the Archean a...

Anthropocene

(Encyclopedia)Anthropocene Epoch, an unofficial term used by scientists to describe a period of time—up to the present—in which humanity has impacted the planet on a global scale. The phrase was fir...

Permian period

(Encyclopedia)Permian period pûrˈmēən [key] [from Perm, Russia], sixth and last period of the Paleozoic era (see Geologic Timescale, tablegeologic timescale, table) from 250 to 290 million years ago. Many ma...

table

(Encyclopedia)table, article of furniture employed for household or ecclesiastical purposes. Elaborately decorated tables of wood or metal were known in ancient Egypt and Assyria, and the Greeks used small tables o...

Pleistocene epoch

(Encyclopedia)Pleistocene epoch plīˈstəsēn [key], 6th epoch of the Cenozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table). According to a classification that considered its depos...

Paleocene epoch

(Encyclopedia)Paleocene epoch pāˈlēəsēnˌ [key], first epoch of the Tertiary period in the Cenozoic era of geologic time (see geologic timescale) between 60 to 66 million years ago. In W North America, the upl...

Elements (table)

(Encyclopedia)Elements 1 Parentheses indicate most stable isotope; brackets enclose lower and upper bounds of weight variation. ...

Constellations (table)

(Encyclopedia)Constellations 1 Zodiac constellation. ...

periodic table

(Encyclopedia)CE5 periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arrange...

water table

(Encyclopedia)water table, the top zone of soil and rock in which all voids are saturated with water. The level of the water table varies with topography and climate, and depends on the degree to which the groundwa...