Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula. [4][5][6] Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen.

In this timeline, Ma (for megaannum) means "million years ago," ka (for kiloannum) means "thousand years ago," and ya means "years ago."

Oceans cooled partly due to the formation of the Antarctic Circumpolar Current, and about 15 million years ago the ice cap in the southern hemisphere started to grow to its present form. The Greenland ice cap developed later, in the Middle Pliocene time, about 3 million years ago.

2018年12月12日 · According to the researchers, if current emission trends continue, then by 2030, Earth’s climate may resemble the mid-Pliocene epoch, which lasted from 3.3 million to three million...

2019年8月21日 · The first primate originated about 25 million years ago, and the first hominid around 3 million years ago. Apes left the trees and walked upright to spot predators in the African grasslands. Homo sapiens dates back to Africa some 300,000 years ago. Early humans showed ingenuity in making tools, creating art, gathering food and hunting.

2023年4月18日 · The last time CO2 levels were as high as today was 3 million years ago during a much warmer time on Earth called the Pliocene. It's a provoking thought for Earth Day.

Fast forward to about 3 million years ago and we see the evolution of the earliest hominids including Sahelanthropus and Australopithecus. The development of hominids saw the first tools and the mastery of fire. Midway through the Quaternary period about 300,000 years ago, the first Homo sapiens in Africa. Over the next hundred thousand years ...

2024年10月17日 · • 4 Billion Years Ago: Earth's crust solidifies; early atmosphere forms. • 3.8 Billion Years Ago: First signs of life appear. • 2.5 Billion Years Ago: Oxygen begins accumulating in the atmosphere.

2025年1月27日 · For 600,000 years during the tail end of the Miocene epoch, the Mediterranean was a dried-up salt plain cut off from the Atlantic Ocean. Around 5.3 million years ago, the eastern and western ...

2019年9月20日 · What was Earth like one million years ago? If our planet is 4.54 billion years old, a million years is not much more than an eyeblink in eternity.