Geology: Formation of Continents and the Geological Timescale

This set of vocabulary flashcards covers the formation of Earth, the history of supercontinents, geological dating principles, the divisions of the geological timescale, and the physical characteristics of modern continents and oceans.

Big Bang Theory

The scientific theory suggesting the Universe originated about $10$ to $20$ billion years ago from a massive cosmic explosion, leading to the formation of Earth around $4.5$ billion years ago.

Rodinia

The first known supercontinent, formed from the earliest solid rocks that appeared between $4600$ and $3900$ million years ago.

Gondwana

A supercontinent that formed near the South Pole by the late Cambrian period ($514$ Ma).

Iapetus Sea

The sea that closed during the mid-Silurian ($425$ Ma) when the Laurasia continent collided with the Baltica continent.

Pangaea

A true supercontinent that came together between $255$–$210$ Ma and began to break apart during the Triassic period ($210$–$180$ Ma).

Panthalassa

The large ocean that surrounded the supercontinent Pangaea approximately $210$ million years ago.

Geological Timescale

A timeframe or timetable developed by Earth scientists to show the possible age of the Earth and its associated life-forms through the study of rocks.

Relative Age

The age of a rock or event determined by analyzing the sequence of geological events without specifying the exact numerical time of origin.

Principle of Original Horizontality

The rule stating that sedimentary layers are originally deposited in nearly horizontal beds under the action of gravity.

Principle of Superposition

The principle that in an undisturbed sequence of sedimentary rocks, the overlying bed is younger than the underlying bed.

Principle of Cross-Cutting Relationships

The rule stating that a rock layer or igneous intrusion that cuts across another layer is younger than the layer it disturbs.

Absolute Age

The actual age of rocks expressed in numerical values (millions of years), determined by measuring radioactive isotopes.

Radioactive Decay

The process by which unstable Parent elements convert into stable Daughter elements through the gaining or losing of particles in their nucleus.

Half-life

The time taken for exactly $50$% of a parent isotope to decay into daughter isotopes.

Precambrian

The longest geological era ($4.5$ billion to $600$ million years ago), covering about $85$% of Earth's history and characterized by the formation of crystalline basement complex rocks.

Paleozoic Era

Known as the 'Age of ancient life' ($600$–$250$ Ma), characterized by trilobites, shelled animals, and the 'Age of fish' (Devonian Period).

Mesozoic Era

Known as the 'Age of Reptiles' or 'Era of Middle Life' ($250$–$70$ Ma), which saw the dominance of dinosaurs and the splitting of Pangaea.

Cenozoic Era

Known as the 'era of recent life' or 'age of mammals' ($70$ Ma to present), which included the emergence of modern humans in the Quaternary Period.

Holocene Epoch

The most recent epoch of the Quaternary Period, covering the last $10,000$ years in which humans live today.

Africa

The second-largest continent and the only one crossed by the Equator, the Tropic of Cancer, and the Tropic of Capricorn.

Australia

The smallest continent, completely surrounded by water and often called an 'island continent' or Oceania.

Mariana Trench

The deepest point in the Earth's oceans, located in the Pacific Ocean at a depth of $10,924$ m.

Southern Ocean

The newest recognized ocean (officially defined in $2000$), extending from the coast of Antarctica to $60^\text{o}$ south latitude.

Puerto Rico Trench

The deepest point in the Atlantic Ocean, reaching a depth of $8,605$ m.