The word "eon" is correct and usable in written English.
It is usually used to refer to a long period of time, usually much longer than a human lifespan. For example, "The ship has been stuck at sea for an eon."
The Cambrian differed greatly from modern times, but it was also quite different from the preceding Proterozoic Eon (2.5 billion to 541 million years ago) in terms of climate, geography, and life.
The positions of the microcontinents that later came together to form Asia are rather uncertain, but many of them probably were either attached or adjacent to the northern margin of Gondwana and migrated north to fuse with the growing area of Asia at several junctures during the later Phanerozoic Eon.
For example, the major groups of marine animals such as mollusks and arthropods appeared for the first time about 541 million years ago at the base of the Cambrian Period of the Phanerozoic Eon.
And at the end of the eon, he will dance the universe to destruction.
Less formally, eon often refers to a span of one billion years.
Nevertheless, most, if not all, of the essential building blocks of proteins (amino acids), carbohydrates (sugars), and nucleic acids (nucleotide bases)—that is, the monomers can be readily produced under conditions thought to have prevailed on Earth in the Archean Eon.
Judaism, consequently, was presented not as a religion of immutable truths but as one for which each cycle, or eon, was said to have a different Torah.
Orogenic deformation in the Altaids was essentially continuous from the late Proterozoic Eon (about 850 million years ago) into the early part of the Mesozoic Era (about 220 million years ago), in some regions such as Mongolia and Siberia lasting even to the end of the Jurassic Period (about 145 million years ago).
About 541 million years ago, at the onset of the Cambrian Period, intense diversification resulted in more than 35 new animal phyla; however, new discoveries show that the "explosion" started roughly 575 million years ago, near the end of the Proterozoic Eon (2.5 billion to 541 million years ago), with the Ediacara fauna.
The Phanerozoic, the eon of visible life, is divided into three major spans of time largely on the basis of characteristic assemblages of life-forms: the Paleozoic (541 million to 252 million years ago), Mesozoic (252 million to 66 million years ago), and Cenozoic (66 million years ago to the present) eras.
For the believing Christian of the original period of the church, the Holy Spirit was the Spirit of the Lord Jesus Christ, who is already now made manifest in his body, the community of the faithful, as the miraculous principle of life of the new eon.
