Chronology - Topics

The iridium anomaly at the K-Pg boundary: how the Alvarez team found an asteroid The Permian-Triassic clay layer that marks 96 percent of marine species gone Sealing a capsule with stainless steel and silica gel under inert gas Why the Quaternary was redefined and the Holocene start moved to 11700 years ago Geological periods are defined by rock layers and their absolute dates are a separate layer of work Tree rings pinned the Norse settlement at L'Anse aux Meadows to a single year Carbon-14 runs out at about 50000 years and deeper time needs other isotopes Egyptian king lists and the Sothic cycle dated pharaohs before radiocarbon existed Dendrochronology and radiocarbon dating do not always agree — what do you do then? When two chronicles contradict each other the first move is to compare their dates of composition not their facts Radiocarbon dating is useless without the calibration curve and the curve rewrote Egyptian chronology Paleography: deciding whether a charter is a tenth-century original or a twelfth-century copy Why is 776 BC the start of Greek history when the Olympics were not the only thing happening? The Anthropocene was voted down in 2024: why geologists refused to end the Holocene What is the difference between a relative sequence and an absolute date? Tree rings can date a Viking timber to the exact felling year Regnal years make you count from the king's accession and not from January 1582 lost ten days and nobody who went to bed on the fourth of October woke up on the fifth Siccar Point in 1788: the unconformity that made deep time thinkable Why does a date in an old English document look ten days early? Julian and Gregorian calendars disagree and the gap keeps growing How do you write a date whose uncertainty is fifty years? Crawford Lake in Canada was proposed as the Anthropocene's golden spike Why calibrated radiocarbon ranges are lopsided rather than symmetric Archives file by provenance first and by date second and the order matters A parish register's entries are not in the order the volume was written The Crypt of Civilization stays sealed until 8113 Double-entry bookkeeping taught merchants to think in irreversible sequences What actually survives a century underground and what turns to mush Egyptian king lists overlap because co-regencies were normal An Assyrian record of a solar eclipse fixed the reign of an entire dynasty Westinghouse buried a capsule in 1939 with instructions for the year 6939