Earth Science 1.2

A View of Earth

Earth’s Major Spheres

Earth is divided into 4 major spheres

HydrosphereAtmosphereGeosphereBiosphere

HydrosphereAll the water on Earth makes up the

hydrosphere.

Oceans account fo r 97% o f a l l wa te r on Ear th

Groundwater, lakes , s t reams, and g lac ie rs account fo r the o ther 3%

Atmosphere The a t m osphe r e i s

t he l i f e sus t a i n i ng , t h i n , gas eous enve lope t ha t su r r ounds t he Ea r t h

I t r eaches 100 k i l om e t e r s above Ea r t h

90% o f i t occu r s w i t h i n 16 m i l es above Ea r t h

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 minera ls

I t is d iv ided in to three main par tsThe core The mant leThe c rus t

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 sectionsOuter coreInner core

Inner Core Earth’s Inner Core

I s a sphere hav ing a rad ius o f 1220 km

Desp i te h igh tempera tu res , the t remendous p ressu re compresses the inne r co re to a so l i d s ta te o f i ron -n i ck le

Outer Core

Earth’s outer coreIs 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 MantleE a r t h ’ s m a n t l e i s t h e l a y e r t h a t l i n k s

t h e E a r t h ’ s c r u s t t o t h e E a r t h ’ s o u t e r c o r e

E a r t h ’ s m a n t l e i s d i v i d e d i n t o t w o p a r t s U p p e r m a n t l e : e x t e n d s f r o m

a b o u t 7 0 k i l o m e t e r s t o 7 0 0 k m

L o w e r m a n t l e : e x t e n d s f r o m a b o u t 7 0 0 k m t o 2 9 0 0 k m

T h e r o c k s o f t h e m a n t l e a r e p a r t i a l l y m o l t e n , o r m e l t e d . T h e y a r e a b l e t o s l o w l y f l o w b e c a u s e o f t h e u n e v e n d i s t r i b u t i o n o f h e a t d e e p w i t h i n t h e e a r t h . T h i s r e g i o n i s c a l l e d t h e a s t h e n o s p h e r e

Earth’s Crust T h e e a r t h ’ s c r u s t

e x t e n d s f r o m 3 m i l e s t o 3 0 m i l e s ( 5 - 7 0 k i l o m e t e r s )

T h e e a r t h ’ s c r u s t i s t h i n n e s t b e n e a t h t h e o c e a n s a n d t h i c k e s t b e n e a t h t h e c o n t i n e n t s

T h e c r u s t a n d u p p e r m o s t m a n t l e m a k e u p a r i g i d o u t l a y e r t h a t i s c a l l e d t h e l i t h o s p h e r e

Earth’s Biosphere E a r t h ’ s b i o s p h e r e i n c l u d e s

a l l l i f e o n E a r t h

I t i n c l u d e s a z o n e t h a t e x t e n d s f r o m t h e o c e a n f l o o r u p w a r d s e v e r a l m i l e s i n t o t h e a t m o s p h e r e

T h e b i o s p h e r e i n c l u d e s a l l p l a n t s a n d a n i m a l s , a l l l i v i n g o r g a n i s m s o n E a r t h

A l l l i v i n g o r g a n i s m s i n t e r a c t w i t h t h e i r e n v i r o n m e n t a n d h e l p m a i n t a i n a n d a l t e r t h e i r p h y s i c a l e n v i r o n m e n t

Biospheres Sc ien t i s t s , i n

a t temp ts to unde rs tand Ea r th ’s b iosphe re , have bu i l t sea led env i ronmen ts tha t a re a r t i f i c i a l b iosphe res

These b iosphe res a re used to s tudy the l i f e p rocesses and i n te rac t i ons o f a l l pa r t s o f an eco log i ca l sys tem

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 I n t he l as t seve ra l decades a

t heo ry has emerged t ha t t he ea r t h ’s l and masses have been i n movemen t s l ow ly ove r t ime

The i dea t ha t Ea r t h ’s con t i nen t s we re once a l l a s i ng le l and mass ca l l ed Pangaea

Continental Drift The theory ex is ts

tha t over t ime Pangaea broke up and the con t inen ts d r i f t ed g radua l l y to the i r p resent loca t ions

Th is i s ca l led the theory o f con t inen ta l d r i f t

Plate Tectonics

What makes the theory o f con t inen ta l d r i f t a poss ib i l i t y i s p la te tec ton ics

Cur ren t l y there a re 7 ma jo r p la tes tha t the Ear th i s d iv ided in to as we l l as severa l sma l le r p la tes

N o r t h A m e r i c a n P l a t eP a c i f i c P l a t eA u s t r a l i a n P l a t eE u r a s i a n P l a t eA f r i c a n P l a t eA n t a r c t i c P l a t eS o u t h A m e r i c a n P l a t e

Plate Tectonics The rubb ing

toge ther o r g r ind ing o f p la tes g r ind ing aga ins t each o ther c rea te fau l t l i nes wh ich account fo r Ear thquakes

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