1. Land erosion
   Continental change
2. Continental​ shift
   Continental​ drift

The theory of continental drift was developed by analyzing the fossils of plants in Norway. Many of the fossils showed evidence of plants that could only grow in the tropics, which was strange considering Norway was near the Arctic.

1. Charles Darwin
   Alfred Wegener
2. James Hutton
   William Smith

A German researcher, Alfred Wegener dedicated his life to studying the polar environment. However, he's most associated with continental drift, a theory that the scientific community rejected until after his death.

1. Plate pull
   Plate tightening
2. Convergent boundaries
   Merging boundaries

The Andes Mountains in South America were formed from a convergent boundary. Stretching the length of South America, these mountains make up the longest mountain range in the world.

1. Water
   Magma
2. Granite
   Mercury

Magma can only be found below the earth's surface. Once magma reaches the surface level, it is known as lava, which is what flows from a volcano​.

1. Mesosphere
   Lithosphere
2. Asthenosphere
   Core

The lithosphere is thinnest in the ocean, where it runs about 10 miles deep. On continents, the lithosphere is upward of 20 miles deep.

1. Subduction
   Gravitational pull
2. Slab pull
   Slab drag

The effects of gravity do not stop at the earth's surface. Instead, gravity pulls everything, including slabs of rock, as far into the earth as they will go.

1. Trench tracking
   Plate sinking
2. Slab pull
   Mantle breakage

Slab pull is believed to be the main cause of tectonic plates shifting. The pull occurs because the dense plate can't hold up on top of the softer mantle beneath.

1. Big/small
   Large/tiny
2. Full/partial
   Major/minor

Another group of tectonic plates known as microplates form along the boundaries of larger plates. These plates develop from the spreading of ridges.

1. 4
   6
2. 7
   9

There are many methods today used to determine the movement of tectonic plates. One of the main methods involves remote sensing satellite​ data.

1. The Pacific Plate
   The Himalayan Plate
2. The Atlantic Plate
   The Nuna Plate

The Pacific Plate is currently shrinking, which means the Pacific Ocean is getting smaller. As it grows smaller, the Atlantic Ocean expands in size.

1. Eurasian Plate
   The North American Plate
2. African Plate
   South American Plate

Obviously, the North American Plate consists of North America, but it also includes Greenland and part of Iceland. According to data, the plate moves a few centimeters per year.

1. Indo-Australian Plate
   African Plate
2. Eurasian Plate
   The South American Plate

The South American Plate extends into the Atlantic Ocean where it meets the African Plate. At the point where the two plates meet, the Mid-Atlantic Ridge forms.

1. Arabian Plate
   Philippine​ Sea Plate
2. Caroline Plate
   Nazca Plate

The Nazca Plate is considered young compared to other tectonic plates. It formed when the Farallon Plate broke apart nearly 23 million years ago.

1. Somali Plate
   Cocos Plate
2. Carribean Plate
   Scotia Plate

The Somali Plate is moving away from the coast of Africa. As the course of the plate continues, it will break away from Africa after millions of years, forming a new continent.

1. Coral spread
   Underwater spread
2. Seafloor spreading
   Ocean spreading

Seafloor spreading occurs at different paces. Where seafloor spreading is slowest, tall underwater cliffs form.

1. Sedimentary rock
   Igneous​ rock
2. Metamorphic rock
   Clastic rock

There are hundreds of types of igneous rocks that form from magma. A few of the more common examples include tuff, granite and obsidian.

1. The stratosphere
   The mesosphere
2. The core
   The asthenosphere

Rocks are liquified in the asthenosphere because of built-up​ heat and pressure. Strangely, the core, which is below the asthenosphere, is solid.

1. Mantle plume
   Mantle spring
2. Mantle hike
   Mantle release

Mantle plumes are a way of cooling off the interior of the earth. Though it's still up for debate, some scientists believe mantle plumes help cool all the way to the core of the earth.

1. Divergent boundary
   Convergent boundary
2. Transform​ boundary
   Slip boundary

Transform boundaries do not slide gracefully past one another. Instead, friction in the rock builds until it eventually gives and breaks apart.

1. Reverse fault
   Normal fault
2. Transcurrent fault
   Strike-slip fault

Normal faults eventually spread apart forming valleys, known as grabens, inside the fault. Currently, the African Plate is splitting in such a way that it will form many of these grabens.

1. Collision fault
   Strike-slip fault
2. Reverse fault
   Transform fault

Faults can form visible cliffs or sloops on the earth's surface. In reverse faults, these are seen where two plates collide, pushing the hanging wall upward.

1. Basalt
   Limestone
2. Granite
   Marble

Mars contains a shield volcano formed from basaltic lava known as Olympus Mons. It is the largest volcano discovered so far in our solar system.

1. Mantle
   Sial
2. Flint
   Sandstone

Sial comes from the words "silicate" and "aluminum." The name is derived from these words because they are the most common minerals in the continental crust.

1. Lithium
   Carbon
2. Sulfur
   Magnesium

Sima is composed of the minerals that make up the oceanic crust. Sima is thinner but denser than continental crust, or sial.

1. Coral reef
   Mangrove
2. Thunderstorm
   Earthquakes

The Valdivia earthquake in 1960 was the largest earthquake ever recorded. When it hit Chile, the earthquake measured at a magnitude of 9.5.

1. San Andreas Fault
   Independence Valley Fault
2. Longmen Shan Fault
   Motagua Fault

The San Andreas Fault is responsible for many of the earthquakes that occur in California. One of the most deadly earthquakes from the San Andreas Fault occurred in 1906 when nearly 3,000 people died.

1. Kermadec Trench
   Mariana Trench
2. Puerto Rico Trench
   Philippine Trench

The Mariana Trench contains the Challenger Deep, the deepest part of the ocean. It is measured at 36,000 feet below sea level.

1. Over
   Under
2. Neither

The Mariana Plate is smushed between the Philippine Sea Plate and the Pacific Plate. Scientists believe it formed when the Philippine Sea Plate broke apart from the pressure of the Pacific Plate subducting underneath it.

1. African Plate
   South American Plate
2. Pacific Plate
   The Indian Plate

Mount Everest stands at an elevation of over 29,000 feet. The mountain continues to grow each year by about a quarter of an inch.

1. The Volcanic Ridge
   The Circle of Fire
2. The Ring of Fire
   The Ring of Volcanoes

Around 90 percent of the earthquakes around the world occur in the Ring of Fire. The region also contains nearly 75 percent of the world's volcanoes, making it a deadly home for the inhabitants.

1. A tsunami
   A coral reef
2. An atoll
   An island

Japan is an island nation that constantly deals with the threat of facing a tsunami. One tsunami in 2011 caused by the Tohoku earthquake killed over 15,000 people in the country.

1. The African Plate
   The Eurasian Plate
2. The Australian Plate
   The Arabian Plate

The main reason the Australian Plate has merged with the Indian Plate is that the Indian Plate's progression northward has been halted by the Himalayas. This causes the Indian Plate to move much slower than the Australian Plate, which is pushing up against it.

1. Crater lake
   Rift lake
2. Organic lake
   Glacial lake

The East African Rift is a continental rift located on a divergent plate boundary in Africa. The rift is responsible for forming the Rift Valley Lakes.

1. Lake Baikal
   Lake Victoria
2. Lake Superior
   Lake Michigan​

Nearly one-fifth of all fresh water in the world is located in Lake Baikal. That water fills the lake to a depth of 1,600 meters.

1. The Indian Plate
   The Cocos Plate
2. The Scotia Plate
   The Arabian Plate

The Red Sea famously runs into the Suez Canal. The canal connects Europe and the Mediterranean to the Arabian Sea, which leads to Asia.

1. Assyria
   Babylonia
2. Pangaea
   Carthage

One of the main sources of evidence for Pangaea's existence are fossils, which are now spread across multiple continents. For example, fossils of the reptile Mesosaurus have been found in both Brazil and West Africa.

1. Center earthquake
   Intraplate earthquake
2. Pivot earthquake
   Core earthquake

The United States' Midwest region contains an intraplate fault known as the New Madrid Fault Line. The fault was responsible for a series of earthquakes in 1811 and 1812.

1. Nanism
   Microseism
2. Tectonism
   Katabolism

When it comes to important minerals and natural resources, you won't find a better source than the lithosphere. The lithosphere contains everything from coal to oil to metals.

1. Seismic wave
   Microwaves
2. Gamma rays
   Infrared waves

Seismic waves are divided into two main categories. Body waves travel through the interior of the earth, where surface waves only move across the surface of the planet.

1. Botany
   Anatomy
2. Systematics
   Topography

One important component studied in topography is elevation. Elevation determines the height of landforms in relation to sea level.