The Precambrian is the vast expanse of time from 4,600 million years until 542 million years ago—a period of nearly 90 percent of Earth’s history. During this time, the Earth coalesced from fragments of rock. As the surface cooled, oceans formed, and the first simple life forms appeared.
Shown below are the Precambrian displays in the Raymond M. Alf Museum of Paleontology on the campus of the The Webb Schools, a private residential high school, in Claremont, California.
The Precambrian is divided into three eons: Hadean, Archean, and Proterozoic. While the Precambrian makes up most of the Earth’s history, relatively little is known about it due to the poor fossil record. Possible evidence of the earliest forms of life comes from islands off western Greenland which date to 3.6 billion years ago and from Western Australia where microscopic fossils of bacteria dating to 3.46 billion years ago. Multicellular life forms first appeared about 1.5 billion years ago.
According to the display at the Raymond M. Alf Museum of Paleontology:
“Life persisted against the odds, through asteroid impacts, volcanic eruptions, global ice sheets, and a thin, poisonous atmosphere. From a tentative toehold in the early oceans, the first glimmers of our modern biosphere appeared. An explosion of life was underway.”
According to the Museum display:
“Called stromatolites, these fascinating fossilized limestone lumps are formed through an accumulation of layers of fine-grained sediments that adhered to algai colonies in shallow-water environments.”