Earth Science 1.2 A View of Earth

Earth’s Major Spheres  Earth is divided into 4 major spheres Hydrosphere Atmosphere Geosphere Biosphere

Hydrosphere All the water on Earth makes up the hydrosphere. Oceans account for 97% of all water on Earth Groundwater, lakes, streams, and glaciers account for the other 3%

Atmosphere  The atmosphere is the life sustaining, thin, gaseous envelope that surrounds the Earth  It reaches 100 kilometers above Earth  90% of it occurs within 16 miles above Earth

Atmosphere  Earth’s atmosphere Provides the air we breath Protects us from sun’s heat and radiation The energy exchange between space, the atmosphere, and Earth’s surface produce weather and climate

Geosphere  The Geosphere is composed of the Earth’s rocks and minerals  It is divided into three main parts The core The mantle The crust

Earth’s Core  Earth’s core is the region in the earth’s center that is composed primarily of iron-nickle alloy  It is divided into two sections Outer core Inner core

Inner Core  Earth’s Inner Core Is a sphere having a radius of 1220 km Despite high temperatures, the tremendous pressure compresses the inner core to a solid state of iron- nickle

Outer Core  Earth’s outer core Is a liquid layer about 2260 km thick composed of flowing iron-nickle The flow of metallic iron in this zone creates the earth’s magnetic fields

Earth’s Mantle Earth’s mantle is the layer that links the Earth’s crust to the Earth’s outer core Earth’s mantle is divided into two parts Upper mantle: extends from about 70 kilometers to 700 km Lower mantle: extends from about 700 km to 2900 km The rocks of the mantle are partially molten, or melted. They are able to slowly flow because of the uneven distribution of heat deep within the earth. This region is called the asthenosphere

Earth’s Crust  The earth’s crust extends from 3 miles to 30 miles ( 5-70 kilometers)  The earth’s crust is thinnest beneath the oceans and thickest beneath the continents  The crust and uppermost mantle make up a rigid out layer that is called the lithosphere

Earth’s Biosphere  Earth’ s biosphere includes all life on Earth It includes a zone that extends from the ocean floor upward several miles into the atmosphere The biosphere includes all plants and animals, all living organisms on Earth All living organisms interact with their environment and help maintain and alter their physical environment

Biospheres  Scientists, in attempts to understand Earth’s biosphere, have built sealed environments that are artificial biospheres  These biospheres are used to study the life processes and interactions of all parts of an ecological system

Earth: a dynamic planet  Earth is a dynamic planet, it is always in change even though some of the changes happen so slowly that we do not easily notice them  Forces that are affecting the Earth constantly Destructive forces (erosion and weathering) Constructive forces ( volcanoes and mountain building)

Pangaea  In the last several decades a theory has emerged that the earth’s land masses have been in movement slowly over time  The idea that Earth’s continents were once all a single land mass called Pangaea

Continental Drift  The theory exists that over time Pangaea broke up and the continents drifted gradually to their present locations  This is called the theory of continental drift

Plate Tectonics  What makes the theory of continental drift a possibility is plate tectonics  Currently there are 7 major plates that the Earth is divided into as well as several smaller plates North American Plate Pacific Plate Australian Plate Eurasian Plate African Plate Antarctic Plate South American Plate

Plate Tectonics  The rubbing together or grinding of plates grinding against each other create fault lines which account for Earthquakes

Plate Tectonics  Plate tectonics accounts for much of the constructive forces that create new land materials  When plates separate materials from beneath the Earth’s surface flow forth in the form of volcanic actions. This accounts for the creation of mountain ranges and creation of new land masses