Astronomers believe the Earth began to accrete more than 4.6 billion years ago.
According to the reigning hypothesis, about 4.5 billion years ago, shortly after Earth had accreted down into a sphere from its little slub of circumsolar material, another newborn planet [Theia], still shaky on its feet, slammed obliquely into Earth with terrifying force.2014 September 7, Natalie Angier, “The Moon comes around again [print version: Revisiting a moon that still has secrets to reveal: Supermoon revives interest in its violent origins and hidden face, International New York Times, 10 September 2014, p. 8]”, in The New York Times:
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Chris Ormel, an astronomer at the University of Amsterdam, and his colleagues recently calculated that protoplanets began to form at the snow line around the star, then grew quickly by accreting pebbles.2018 April 26, Alexandra Witze, “Earth May Have Been Formed by a Bunch of Tiny Space Pebbles”, in The Atlantic:
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To adhere; to grow or to be added to gradually.
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To make adhere; to add; to make larger or more, as by growing.
the reader has not only mastered this distinction , but that he has so thoroughly accreted it and assimilated it to his habits of mind1871, John Earle, The Philology of the English Tongue: