when did the current geologic epoch begin and what event marked its beginning
Holocene The Holocene ( /ˈhɒləˌsiːn, ˈhoʊ-/)[2][3] is the current geological epoch. It began approximately 11,650 years before present, after the last glacial period.[4] The Holocene and the preceding Pleistocene[5] together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1, and is considered by some to be an interglacial period.
K–Ar dating Due to the long half-life, the technique is most applicable for dating minerals and rocks more than 100,000 years old. For shorter timescales, it is unlikely that enough argon-40 will have had time to accumulate in order to be accurately measurable. K–Ar dating was instrumental in the development of the geomagnetic polarity time scale.[2] Although it finds the most utility in geological applications, it plays an important role in archaeology. One archeological application has been in bracketing the age of archeological deposits at Olduvai Gorge by dating lava flows above and below the deposits.[8] It has also been indispensable in other early east African sites with a history of volcanic activity such as Hadar, Ethiopia.[8] The K–Ar method continues to have utility in dating clay mineral diagenesis.[9] Clay minerals are less than 2 micrometres thick and cannot easily be irradiated for Ar–Ar analysis because Ar recoils from the crystal lattice.