Grade 11 Geography unit 6: Major global environmental changes

The universe originated 10 to 20 billion years ago, but the Earth was created from gas and dust particles about 4.5 billion years ago.

Africa is the only continent on Earth that is crossed by all three lines of latitude: the Equator, the Tropic of Cancer, and the Tropic of Capricorn.

The deepest point in the world is the Challenger Deep within the Mariana Trench in the Pacific Ocean, reaching a depth of about 10,924 meters.

The principle of superposition states that in an undisturbed sedimentary rock sequence, older layers are at the bottom and younger layers are deposited on top.

In the Northern Hemisphere, the ratio of land to ocean is about 1:1.5, whereas in the Southern Hemisphere, it is 1:4 due to the vast coverage of water.

After one half-life, 50% of the parent isotope remains. After two half-lives, that amount is halved again, leaving 25% parent isotope and 75% daughter product.

The Devonian period, which lasted from 360 to 408 Ma, was rich in fish species and is called the age of fish.

The landmass that became the Indian sub-continent separated from Gondwana at about 140 Ma and drifted north to collide with Eurasia, creating the Himalayan mountain range.

Potassium-40 (⁴⁰K) decays into Argon-40 (⁴⁰Ar) with a half-life of 1.25 billion years.

The Atlantic Ocean drains massive river systems such as the Amazon, Congo, Mississippi, and St. Lawrence, receiving more continental freshwater runoff than any other ocean.