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