GEOG1040 Dynamic Landscapes - Lecture 15: Deep Time: A Brief History of Absolutely Everything

Vocabulary flashcards covering the major geological timescales, terminology, symbols, and critical chronological milestones from Lecture 15 of GEOG1040 Dynamic Landscapes.

Eon

The broadest division of geological time, with either three or four eons recognised since the formation of the Earth.

Phanerozoic

The current geological eon, which began approximately $540\text{ million years ago}$ when the first hard-shelled creatures developed in the ocean.

Era

The broadest subdivision of an eon, spanning at least a hundred million years; eleven have occurred since the formation of the Earth.

Cenozoic

The current geological era, which began $65\text{ million years ago}$ with the Cretaceous-Palaeogene extinction event.

Period

The broadest subdivision of an era, currently exemplified by the Quaternary period.

Quaternary

The current geological period, which began $2.59\text{ Ma BP}$ when Earth's climate began oscillating between warm (interglacial) and cold (glacial) phases.

Epoch

The broadest subdivision of a period, lasting at least several thousand years and potentially much longer.

Holocene

The current geological epoch, which began $11,650\text{ years ago}$ ($11.65\text{ ka BP}$) once the majority of ice had melted after the northern hemisphere's most recent glaciation.

Ga (or GY)

A geological symbol representing one billion years ($1,000,000,000\text{ years}$ or $10^9\text{ years}$).

Ma (or My)

A geological symbol representing one million years ($1,000,000\text{ years}$ or $10^6\text{ years}$).

Ka (or Ky)

A geological symbol representing one thousand years ($1,000\text{ years}$ or $10^3\text{ years}$).

0 BP

The standard baseline date for "Before Present" geological time, established as the year $1950\text{ AD}$ so that calculated ages of past events remain constant.

Tertiary

A defunct geological period ($65\text{ to }2.6\text{ Ma BP}$) that was recently subdivided into the Palaeogene and Neogene periods.

Stromatolites

Fossilised bacterial mats dating to $3.8\text{ to }3.7\text{ Ga BP}$, representing Earth's oldest known fossil organisms.

Ediacaran biota

Sessile organisms dating to $575\text{--}543\text{ Ma BP}$ that provide the earliest evidence of multicellular eukaryotic life.

Cambrian "Explosion"

A dramatic expansion and diversification of life around $540\text{ Ma BP}$, marked by the development of hard-shelled creatures, insects, fish, complex plants, and a vastly improved fossil record.

Cretaceous-Palaeogene extinction event

A mass extinction event occurring $65\text{ Ma BP}$ that wiped out the dinosaurs and the majority of other animals and plants, enabling mammals and birds to rise to dominance.

Last Glacial Maximum (LGM)

The interval from $26.5\text{ to }19\text{ ka BP}$ when ice sheets reached their maximum extent and sea levels reached their lowest during the most recent glaciation.

Devensian

The regional name used in Britain to designate the Earth's most recent glaciation.

Homo sapiens

Anatomically-modern humans whose oldest known fossil remains date to approximately $300\text{--}150\text{ ka BP}$.