Dating back to the precambrian era

The Precambrian is sometimes referred to as an "eon." However, it actually has no rank. The Precambrian is that stretch of geological time from the formation of the Earth itself to the start of the Cambrian period.

This immensely long stretch of time - some four billion years or more - saw the formation of the Earth as a planetary body, including geosphere, atmosphere, and hydrosphere, as well as the appearance of the biosphere and hence the transformation of the Earth from a dead planet to a living one.

During the eighteenth century geologists first began mapping the strata of the earth's crust.

dating back to the precambrian era-63

These were called the "Primitive" or "Primary", although the term "Primary Era' later came to be applied to the oldest sedimentary stage (later to be called the Paleozoic).

In 1835 the English geologist Adam Sedgwick used the name "Cambrian" for the oldest sedimentary strata.

Thereafter the underlying rocks were term Precambrian - "before the Cambrian".

During the twentieth century the term "Cryptozoic" - age of hidden life" - was used to designate this period, whilst Phanerozoic - "age of obvious (or revealed) life" - was used for those periods from which fossils of multicellular organisms are known (i.e. Although the latter term is still in use, "Cryptozoic" pretty much disappeared in favor of the older and well established Precambrian. 1., Oasis in space: Earth history from the beginning - Time, Life, Evolution, Earth, Million, and Eon, based on a diagram by Preston Cloud.

(Cloud 1988), showing the chemical and mineralogical evolution of the Earth's crust and atmosphere, along with impact craters, glaciation events, and the evolution of life.

Although life appears fairly early, following a period of prebiotic chemical evolution, it is only towards the end of the Precambrian that complex organisms arise.A newer version of geological eras and the Precambrian, from Wikipedia.As shown here, the Precambrian includes by far the majority of geological time.Much of this immensely long interval dominated almost entirely by microbial (and there mostly simply bacterial) life.The fleeting periods shown as narrow coloured bars to the the far right of the chart represent the familiar Phanerozoic geological timescale, characterised by life above the microbial and algae mat stage.Because Precambrian time is so long, it is useful to divide it into stages or eons.

Tags: , ,