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Earth's surface is the boundary between the atmosphere, and the solid Earth and oceans. Defined in this way, it has an area of about 510 million km 2 (197 million sq mi). [12] Earth can be divided into two hemispheres: by latitude into the polar Northern and Southern hemispheres; or by longitude into the continental Eastern and Western hemispheres.
Geologic time shown in a diagram called a geological clock, showing the relative lengths of the eons of Earth's history and noting major events. The geological history of Earth follows the major geological events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock ...
Landforms are categorized by characteristic physical attributes such as elevation, slope, orientation, structure stratification, rock exposure, and soil type.Gross physical features or landforms include intuitive elements such as berms, cliffs, hills, mounds, peninsulas, ridges, rivers, valleys, volcanoes, and numerous other structural and size-scaled (e.g. ponds vs. lakes, hills vs. mountains ...
Land is often defined as the solid, dry surface of Earth. [1] The word land may also collectively refer the collective natural resources of Earth, [2] including its land cover, rivers, shallow lakes, its biosphere, the lowest layer of the atmosphere (troposphere), groundwater reserves, and the physical results of human activity on land, such as architecture and agriculture. [3]
Geographers study the Earth's spatial and temporal distribution of phenomena, processes, and features as well as the interaction of humans and their environment. [22] Because space and place affect a variety of topics, such as economics, health, climate, plants, and animals, geography is highly interdisciplinary. The interdisciplinary nature of ...
The five main latitude regions of Earth's surface comprise geographical zones, [1] divided by the major circles of latitude. The differences between them relate to climate. They are as follows: The North Frigid Zone, between the North Pole at 90° N and the Arctic Circle at 66°33′50.3″ N, covers 4.12% of Earth's surface.
Earth's crust and mantle, Mohorovičić discontinuity between bottom of crust and solid uppermost mantle. Earth's mantle extends to a depth of 2,890 km (1,800 mi), making it the planet's thickest layer. [20] [This is 45% of the 6,371 km (3,959 mi) radius, and 83.7% of the volume - 0.6% of the volume is the crust].
Artist's impression of Earth during the later Archean, the largely cooled planetary crust and water-rich barren surface, marked by volcanoes and continents, features already round microbialites. The Moon, still orbiting Earth much closer than today and still dominating Earth's sky, produced strong tides. [104]