What was Earth's surface like 1.6 million years ago?

Answer 1

Earth's surface changed many times during the Precambrian (which is the time between when Earth first formed and when the Cambrian began, and makes up 7/8 of Earth's history).

In the beginning, Earth was a giant mass of magma, but it eventually cooled enough to have a stable crust. Then, water vapor in the atmosphere condensed and fell as rain, eventually covering the Earth in a giant ocean, which was green because of dissolved iron.

Life, (in the form of simple bacteria), first evolved about 3.5 billion years ago. However, it did not change Earth's climate or the appearance of its surface until the first photosynthesizing organisms (which were cyanobacteria) evolved at least 2.8 billion years ago. The oxygen that they produced first oxidized the iron in the oceans, which made the iron sink, and the oceans became blue, as they are today. Eventually, carbon dioxide levels became so low, and oxygen levels so high, that the Earth underwent such dramatic cooling that ice covered the ocean all the way to the Equator for millions of years.

Meanwhile, continents formed, joined together into supercontinents, and then broke back up again. However, the continents were completely different in both shape and position during the Precambrian than they are today.

Lastly, it is important to note that there is no evidence of any form of life on land, nor of multicellular organisms, until after the Precambrian (e.g., the Cambrian).

Answer 2

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