Pertemuan II

BENUA DAN SAMUDERA

Awal terbentuknya Samudera

• Awal terbentuknya Samudera besar di bumi ini juga di pengaruhi oleh Pangea.

• Setelah perpisahan (partisi pangea) muncullah samudera yang diperkirakan terbentuk 180-200 juta tahun yang lalu yaitu Samudera Atlantik tengah antara barat laut Afrika dan Amerika Utara serta Samudera Hindia barat daya antara Afrika dan Antartika.

Teori Alfred WegenerAhli metereologi Jerman, Alfred Wegener menyatakan

bahwa benua terdiri atas batuan sial (silisium aluminium), yang terapung pada batuan sima (silisium magnesium) yang lebih besar berat jenisnya. Benua itu bergerak menuju khatulistiwa dan ke bagian barat. Pada zaman karbon diduga hanya ada satu benua, yaitu PANGEA. Benua Pangea kemudian pecah dan terbentuklah daratan Gondwana (<200 jt thn) setelah zaman karbon. Dalam (180 jt thn) terakhir Gondwana terurai. Mula-mula terpisah menjadi Kutub Selatan dan Benua Australia, kemudian Benua Amerika dan Afrika, akhirnya Greendland dan Benua Eropa.

Break up of Pangaea

The shapes match.The shapes match.

Copyright © 2010 Ryan P. Murphy

Same fossils found on different Same fossils found on different continentscontinentsThese are the pictures on the puzzle These are the pictures on the puzzle

pieces.pieces.

Copyright © 2010 Ryan P. Murphy

Sea Floor SpreadingIf the continents are moving apart then the seas between them must begetting wider. This is called sea floor spreading. How do we know thatthis is true?

First, a series of under-water mountains called mid-ocean ridges is found throughout the world. These mountains are formed as new sea floor (basalt) is created from magma that wellsup from the mantle below.

As new sea floor is addedit pushes the old sea floorapart.

Proof that this occurs can befound by looking at the ageof the sea floor itself.

New sea floor is found at the mid ocean ridge where material isconstantly being added. As distance from the ridge in eitherdirection increases, so does the age of the rock.

Continental margins: where land meets the sea

Atlantic Ocean: plate boundary is in the center of the ocean basin, away from the continental margin

Samudera di dunia

No Nama Samudera

Luas ( km ² )

1234

Pasifik AtlantikHindiaArktik

166.000.000.00082.000.000.00073.400.000.00014.100.000.000

BENUA DI DUNIA

NO NAMA BENUA LUAS ( km² )% dari seluruh dunia

123456

ASIAAMERIKAAFRIKAEROPAAUSTRALIAANTARTIKA

44.493.00042.292.00030.970.00010.245.000

8.945.00015.500.000

29,2 %27,7 %20,3 %

6,7 %5,9 %

10,2 %

Tabel 3. Samudera di dunia

No Nama Samudera

Luas ( km ² )

1234

Pasifik AtlantikHindiaArktik

166.000.000.00082.000.000.00073.400.000.00014.100.000.000

World Ocean FactsArea

(1,000,000 km²)

Volume(1,000,000

km³)

Average Depth

(m)

Maximum Depth

(m)

Atlantic Ocean 82.4 323.6 3926 9200

Pacific Ocean 165.2 707.6 4282 11,022

Indian Ocean 73.4 291.0 3963 7460

Arctic Ocean 14.1 17.0 1205 4300

Why Study Oceanography?

• Oceans comprise 71% of the Earth’s surface

• Oceans contain 97.2% of the water on or near the Earth’s surface

• Source of Food• Transportation and Travel• Weather• Shoreline

– Interface between land and ocean

The World Ocean

© 2011 Pearson Education, Inc.

Earth’s Oceans

• Earth has one ocean.• It is divided into four

principle oceans, and one other.– Pacific Ocean– Atlantic Ocean – Indian Ocean– Arctic Ocean– Southern, or Antarctic

Ocean

The 5 Oceans Pacific Ocean

– Largest and deepest ocean– Mariana Trench: 11 km., 36,000 ft.

(Mt. Everest 29,000 ft.) Atlantic Ocean

– About ½ the size of the Pacific Indian Ocean

– Southern hemisphere Arctic Ocean

– ¼ as deep, much smaller, sea ice Southern Ocean

– South of 50 deg. South latitude

Distribution of land and sea by latitude

© 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

Ocean Size and Depth

© 2011 Pearson Education, Inc.

Earth’s Oceans

• Pacific Ocean – World’s largest ocean

• Accounts for more than half of Earth’s ocean space

– World’s deepest ocean– Earth’s largest geographic feature– Named in 1520 by Ferdinand Magellan

• Arctic Ocean–Seven percent the size of the

Pacific Ocean–Shallowest world ocean–Permanent layer of sea ice a few

meters thick• Southern Ocean or Antarctic Ocean

–Circumnavigates Antarctica–Is really the parts of the Pacific,

Atlantic, and Indian Oceans that lie south of 50° S latitude

© 2011 Pearson Education, Inc.

Earth’s Oceans

• Atlantic Ocean– Half the size of the Pacific Ocean– Shallower than the Pacific Ocean– Separates the Old World from the New World

• Indian Ocean– Smaller than the Atlantic Ocean– Similar depth as the Atlantic Ocean– Primarily in the Southern Hemisphere

© 2011 Pearson Education, Inc.

The Seven Seas

• Smaller and shallower than oceans• Salt water• Usually enclosed by land

– Sargasso Sea defined by surrounding ocean currents

• Directly connected to the ocean

© 2011 Pearson Education, Inc.

The Seven Seas• Before the 15th Century, Europeans

considered the seven seas to be the following:1. Red Sea2. Mediterranean Sea3. Persian Gulf4. Black Sea5. Adriatic Sea6. Caspian Sea7. Indian Ocean

© 2011 Pearson Education, Inc.

Comparing Oceans to Continents• Average ocean depth is 3729

meters (12,234 feet)• Average continental elevation is

840 meters (2756 feet)

• Deepest ocean trench is the Mariana Trench at 11,022 meters (36,161 feet)

• Highest continental mountain is Mt. Everest at 8850 meters (29,935 feet)

Continental Margin and Deep Ocean Basin

• BE A GOOD STUDENT• GET YOUR DREAMS COMES

TRUE

TERIMA KASIH