Dating method for volcanic ash
Lucy and other members of her species, Australopithecus afarensis, lived between 3.9 and 3.0 million years ago.
They are believed to be the most ancient common ancestor, or "stem" species, from which all later hominids sprang. Estimating the age of hominid fossils is usually a painstaking, two-part process, involving both "absolute" and "relative" dating.
The main advantages of the technique are that the volcanic ash layers can be relatively easily identified in many sediments and that the tephra layers are deposited relatively instantaneously over a wide spatial area.
This means they provide accurate temporal marker layers which can be used to verify or corroborate other dating techniques, linking sequences widely separated by location into a unified chronology that correlates climatic sequences and events.
dating method for volcanic ash Why should isign up for webmd?The Laetoli footprints are rare treasures in the record of human ancestry.They are fossils captured in volcanic rock that can be given an absolute date.Major element chemistry of glass shards was determined with electron microprobe analysis on the younger key bed.The older, Messinian-age ash bed, sampled at Maccarone, yields a corrected glass fission-track age of 5.38±0.42 Ma. Angelo and at two localities at Bellante, yields corrected glass ages of ∼2.1 Ma, similar to ages previously determined on Pliocene–Pleistocene ash collected along the Ionic coast and on the Tyrrhenian side of Italy.