Earth History

Sometimes science deals with incredibly large numbers, sometimes with great distances still other times with infinitely small particles. In science we must expand our conception of reality all the time. One of the very difficult concepts is the understanding of TIME. Everyone is conscious of the changes in the physical and biological world; they give us an awareness of time. The daily rhythm, the seasons, physical changes throughout a human lifetime are familiar concepts of time to us. Time is measured by change, but where change occurs over millions of years our own perception of time is on unfamiliar territory. To understand the rhythm of change of our planet and the effects it has on life on Earth we have to expand our perception of time. The geological processes that shape the surface of our planet, move the tectonic plates, build mountains and erode them again work over millions of years. These forces provide the ever changing conditions for life, which adapted to those changes.

The history of Earth covers approximately 4.6 billion years (4,567,000,000 years), from Earth’s formation out of the solar nebula to the present.

Cenozoic Life characterized by proliferation of mammals, insects, and flowering plants Continental Drift has continued with Australia separating from Antarctica and Asia and Africa colliding at Arabia Climate has deteriorated throughout the era, climaxing in a still continuing (in geological terms) ice age.	Quaternary	Holocene 0.01 million years ago	Early Civilizations
		Holocene 0.01 million years ago	Emergence of Man
		Pleistocene 2 million years ago
		Pleistocene 2 million years ago
	Tertiary	Pliocene 7 million years ago	Himalayan Mountains begin
		Miocene 26 million years ago
		Oligocene 38 million years ago
		Eocene 54 million years ago
		Paleocene 65 million years ago
Mesozoic Life was dominated by dinosaurs and marine reptiles in the animal world and gymnosperms among plants. Continental break-up of plates from the old Pangaea (one big continent) Climate was warm and equable over the entire planet	Cretaceous	136 million years ago (Main area of oil zones in Lloydminster region)	seas transgress
	Jurassic	190 million years ago	Pangaea fragments
	Triassic	225 million years ago	seas regress
Paleozoic Life evolved from invertebrates through amphibians to reptiles Continent formed as Pangaea rose out of earlier huge seas Climate alternated between long warm periods and short ice ages	Permian	280 million years ago	formation of Pangaea
	Carboniferous	Pennsylvanian 315 million years ago
	Carboniferous	Mississippian 345 million years ago
	Devonian	395 million years ago	first land animals
	Silurian	440 million years ago	first land plants
	Ordovician	500 million years ago
	Cambrian	570 million years ago	major transgression of seas
Precambrian Life appears and evolves to multicellular organisms Continental and mountain building Climate uncertain, free oxygen emerges	Proterozoic	570 to 2500 million years ago	first multicellular organisms
	Archaean	2500 to 4600 million years ago	the Earth forms

Dimitrie Ghica School