When rocks in the seafloor form, they can contain a record of the strength and direction (polarity) of the Earth's magnetic field. The
diagram below shows this data from rocks on both sides of a mid-ocean ridge.
observed.

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides

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