Tectonic plates and the interior of the Earth Plate Tectonics

catastrophism

The belief that geological changes occur suddenly and are primarily caused by catastrophic events, often linked to a Biblical Flood until the 1700s.

uniformitarianism

A geological principle, proposed by James Hutton, stating that the present is key to the past, meaning geological processes occurring today also occurred in the past.

Continental Drift

A scientific theory proposed by Alfred Wegener suggesting that continents were once joined as a supercontinent (Pangaea) and have since drifted apart.

Pangaea

The supercontinent that existed around 200 million years ago before fragmenting into the continents we know today.

fossil evidence

Remains or traces of ancient organisms, used to support theories of continental drift, especially the presence of identical fossils on separated continents.

seafloor spreading

The process by which new oceanic crust is created at mid-ocean ridges, contributing to tectonic movement.

plate tectonics

The scientific theory explaining the structure and movement of the Earth's lithosphere, which is divided into tectonic plates.

divergent boundary

A tectonic plate boundary where two plates move away from each other, creating new crust.

convergent boundary

A tectonic plate boundary where two plates collide, causing one plate to be subducted under another and resulting in features like trenches and volcanoes.

transform boundary

A tectonic plate boundary where two plates slide past one another horizontally, known for causing earthquakes.

hotspot

A location where volcanic activity occurs far from plate boundaries, caused by a stationary plume of hot material from the mantle.

Moho

The boundary between the Earth's crust and the mantle, named the Mohorovičić discontinuity.

radioactive decay

The process by which an unstable atomic nucleus loses energy by emitting radiation, allowing for radiometric dating of rocks.

index fossil

Fossils of organisms that were widespread and existed for a short geologic timeframe, used to date rock layers.

Law of Superposition

In any undisturbed sequence of rocks, the oldest layers are at the bottom and the younger ones are at the top.

Principle of Original Horizontality

The assumption that sedimentary rock layers are originally deposited horizontally.

Principle of Faunal Succession

A principle stating that fossil organisms succeed one another in a definite and recognizable order, allowing for relative dating of rocks.

Cenozoic Era

The current geological era, which began 65.5 million years ago and is characterized by the dominance of mammals and the evolution of humans.

Precambrian Time

The earliest period in Earth's history, lasting from Earth's formation 4.6 billion years ago to about 540 million years ago, when multicellular life began to appear.

Cambrian Explosion

A rapid diversification of life forms occurring approximately 541 million years ago, marked by the appearance of most major animal groups.

Great Oxidation Event

The period around 2.4 billion years ago when oxygen began to accumulate in Earth's atmosphere due to photosynthetic organisms, altering life on Earth.

Ediacaran Biota

The first complex multicellular life forms that appeared during the late Precambrian period, approximately 635 to 541 million years ago.

Mesozoic Era

The geological era from about 252 million to 66 million years ago, known as the age of dinosaurs, during which they evolved and dominated the Earth.

Anthropocene Era

A proposed geological epoch marked by significant human impact on Earth's geology and ecosystems, often considered to have begun in the 20th century.

absolute dating

A method of determining the exact age of a rock or fossil through radiometric techniques, providing numerical ages.

relative dating

A technique used to determine the age of rocks and fossils in relation to one another, not providing exact dates.