An extinct group of marine animals that lived in the open water of ancient seas, rather than at the sea bottom. Their name came from their spiral shape as their fossilized shells somewhat resemble tightly-coiled rams' horns.

A dark-colored igneous rock that makes up the floors of the oceans and is referred to as ‘oceanic crust.’ Basalt is a common extrusive volcanic rock that is black or grey in colour and fine grained due to the rapid cooling of lava once it reaches the surface of the Earth. Island nations like Hawaii and Iceland are made up overwhelmingly of basalt due to their locations above tectonic hotspots.

The Cambrian Period marks an important point in the history of life on Earth about 500 million years ago. It’s the time when the first complex animals appear in the fossil record. This event is called the "Cambrian Explosion" because of the relatively short time over which this diversity of forms appears.

According to his theory of evolution, Darwin believed that ‘the world swarmed with living creatures’ well before the Cambrian period 500 million years ago. But without proof of these creatures, his theory was vulnerable to attack. Discovery of fossils in early Cambrian rocks at place like Mistaken Point, NFLD, and in the Burgess Shale in British Columbia (the ‘Cambrian Explosion’) prove that Darwin was right in his assumption. Bacteria appear to have been present on planet Earth as early as 3.5 billion years ago, possibly earlier.

Two tectonic plates that are moving away from each other. The process starts as a narrow rift that eventually widens into an ocean basin.

The wearing down of rocks by wind, water, or ice, and gravity.

Hot volcanic ash emitted during an explosive volcanic eruption forms a column rising many kilometres (as many as 40 km) into the air above the volcano. These are a major cause of short-term climate change.

The large crater left by a massive volcanic eruption.

Where two continents collide to form a major mountain chain such as the Alps or Himalayas. The process may take several tens of millions of years before faulting and folding caused by the collision eventually stops. This is currently happening between India and Asia. The process is referred to as ‘orogeny’ meaning ‘to build mountains.’

The movement of the Earth's plates relative to each other, grinding past, moving away from or colliding. The term ‘continental drift’ is no longer used as continents are embedded in larger plates and it is these that migrate.

A layer of rocks that form the continents about 40 to 100 kilometres thick. It is less dense than the material of the Earth's mantle and thus "floats" on top of it. About 40% of the Earth's surface is now underlain by continental crust. The thickest areas of crust are under mountain ranges and continental interiors such as the Canadian Shield. Continental crust is dominated by rocks of granitic affinities or basalt.

The dropping of eroded rock material when the agent of transportation (e.g., wind, rivers, waves) slows down.

Fossils are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms.

Rock fractures, which show evidence of relative movement. They are the location of many earthquakes.

A large, slow moving river of ice, formed from compacted layers of snow that slowly deforms and flows in response to gravity. Glacier ice is the largest reservoir of fresh water on Earth followed by the Great Lakes of North America.

Landscape feature dominant in parts of New Zealand made of sandstone and mudstone.

A geologic period that existed between 200 and 150 million years ago. It was called the ‘age of reptiles.’

A roughly 100,000 year long period of long-term reduction in the temperature of Earth’s climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers. There have been at least 50 major ice ages in the last 3 million years, each one separated by shorter, warmer interglacials.

An area less than 50,000 km2 of ice often found in the colder climates and higher altitudes of the world.

An ocean that existed between North America and ancestral Europe between 400 and 600 million years ago. It was destroyed when parts of Europe collided with North America about 350 million years ago when the supercontinent Pangea formed. The modern day Atlantic Ocean was formed by the breakup of Pangea.

A massive and powerful mudslide with the weight and consistency of wet concrete. These are very common on the flanks of volcanoes where wet ash flows downslope.

A circular shaped bulge resulting from the slow extrusion of lava from the neck of a volcano. These are very dangerous when they collapse to form pyroclastic flows.

A volcanic phenomenon in which lava is forcefully but non-explosively ejected from a crater, vent, or fissure. Lava fountains may reach heights of up to 500 meters.

The solid outer layer of the Earth that includes the crust and the upper part of the mantle

Molten rock located beneath the surface of the earth at a temperature of 700°C to 1300°C. It can be thrust at the surface as lava.

A 2,900 km thick solid rocky shell comprising approximately 70% of Earth's volume. It is solid and overlies the Earth's iron-rich core, which occupies about 30% of Earth's volume.

An upwelling of abnormally hot rock within the Earth's mantle. It’s a way that the Earth loses heat.

Rocky debris left over from the beginnings of the solar system that enters the Earth’s atmosphere and which either burns up completely (to form a meteor) or may survive to hit the Earth’s surface.

Oceanic crust is primarily composed of volcanic rock, or basalt. It is thinner than continental crust and generally less than 10 kilometers thick, but it is denser.

A geologic period that existed 500 – 250 million years ago. Fish, forests and reptiles thrived during this period which ended in a mass extinction triggered by an ice age.

A supercontinent that existed about 250 million years ago, before each of the modern continents were separated into the world’s current configuration. Pangaea was a C-shaped landmass that spread across the equator. A single vast ocean named Panthalassa surrounded the continent. Pangaea is believed to have broken up about 180 million years ago to form the modern oceans.

Eventually, in some 200 million years time, Pangea II will be one large landmass surrounded by one large ocean. There will be no need for long trans-oceanic flights; everywhere in the world will be reachable by land. The future world will be very different from the one humans evolved in and it is a sure bet we won’t be part of it.

The Earth’s crust sits on some twenty large tectonic plates both oceanic and continental, whose movement is controlled in the Earth’s mantle. The mantle sends the plates crashing across the globe, slamming them together to create supercontinents or splitting them apart.

A common and devastating result of some explosive volcanic eruptions. The flows are fast-moving currents of hot gas and rock which travel away from the volcano at speeds generally as great as 700 km/h (450 mph). These are very dangerous to surrounding populations.

A volcano with shallow-sloping sides, out of which pour highly fluid hot lava that can cover great distances. Some of the largest volcanoes on Earth are shield volcanoes such as those on Hawaii.

Tall, conical volcanoes built up by many layers hardened lava and volcanic ash. They usually erupt with explosive force because the magma is too stiff to allow easy escape of volcanic gasses. It can be compared to putting a thumb over an opened bottle of a carbonated drink, shaking it vigorously, and then quickly removing the thumb. Stratovolcanoes often complete their life cycle by exploding, leaving calderas.

An area where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the mantle at rates measured in centimeters per year. An oceanic plate ordinarily slides underneath a continental plate; creating a subduction zone with many volcanoes and earthquakes.

A volcano produced by eruptions beneath the surface of a glacier or ice sheet which is then melted into a lake by the rising lava. They have flattened tops and steep sides that are supported against collapse by the pressure of the surrounding ice and meltwater. The now famous, Eyjafjallajokull is a subglacial volcano.

Stresses created by the movement of tectonic plates that crack (fault) and bend (fold) rocks.

Ejected material-such as rock pieces-from a volcano during an eruption.

A wide ocean that existed during the Mesozoic era between the northern half of Pangea (North America, Europe) and its southern half (Gondwana). The closure of the Tethys Ocean by collision of parts of Gondwana (Africa, India) pushed up the Alps and Himalayas.