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The numeric values on the International Chronostratigrahpic Chart are represented by the unit Ma (megaannum, for 'million years'). For example, 201.4 ± 0.2 Ma, the lower boundary of the Jurassic Period, is defined as 201,400,000 years old with an uncertainty of 200,000 years.
Milli (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth (10 −3). [1] Proposed in 1793, [ 2 ] and adopted in 1795, the prefix comes from the Latin mille , meaning one thousand (the Latin plural is milia ).
For example, 5 km is treated as 5000 m, which allows all quantities based on the same unit to be factored together even if they have different prefixes. A prefix symbol attached to a unit symbol is included when the unit is raised to a power. For example, 1 km 2 denotes 1 km × 1 km = 10 6 m 2, not 10 3 m 2.
Numeral or number prefixes are prefixes derived from numerals or occasionally other numbers. In English and many other languages, they are used to coin numerous series of words. In English and many other languages, they are used to coin numerous series of words.
2.6 × 10 11 Qs (8.2 × 10 33 years): The smallest possible value for proton half-life consistent with experiment [19] 10 23 Qs ( 3.2 × 10 45 years ): The largest possible value for the proton half-life , assuming that the Big Bang was inflationary and that the same process that made baryons predominate over antibaryons in the early Universe ...
[2] [3] [4] Two or more radiometric methods can be used in concert to achieve more robust results. [5] Most radiometric methods are suitable for geological time only, but some such as the radiocarbon method and the 40 Ar/ 39 Ar dating method can be extended into the time of early human life [ 6 ] and into recorded history.
Also called "megayear". 1000 millennia (plural of millennium), or 1 million years (in geology, abbreviated as Ma). petasecond: 10 15 s: About 31 709 791 years. galactic year: 2.3 × 10 8 yr: The amount of time it takes the Solar System to orbit the center of the Milky Way Galaxy (approx 230 000 000 years [2]). cosmological decade: logarithmic ...
The "ago" is implied, so that any such year number "X Ma" between 66 and 145 is "Cretaceous", for good reason. But the counter argument is that having myr for a duration and Mya for an age mixes unit systems, and tempts capitalization errors: "million" need not be capitalized, but "mega" must be; "ma" would technically imply a milliyear (a ...