The resulting rock strata may harbor fossils from a particular habitat area or ecosystem, but do not represent a particular age or era.
Young-earth creation geologists have long held that most sedimentary strata resulted from waterborne deposits during Noah’s Flood.Phenocrysts of orthopyroxene, hornblende and plagioclase are interpreted to have occluded argon within their mineral structures deep in the magma chamber and to have retained this argon after emplacement and solidification of the dacite.The amount of argon occluded is probably a function of the argon pressure when mineral crystallization occurred at depth and/or the tightness of the mineral structure.Obviously both sides of this debate have agendas to promote, and that means that any summary you're likely to read was probably motivated by one agenda or the other.Let's begin with a basic understanding of the radiometric dating technique used, K-Ar, or potassium-argon.Orthopyroxene retains the most argon, followed by hornblende, and finally, plagioclase. Helens dates very much older than its true age because phenocryst minerals inherit argon from the magma. Helens dacite causes the more fundamental question to be asked—how accurate are K-Ar 'ages' from the many other phenocryst-containing lava flows world-wide? Helens in Washington State expressed itself directly during six explosive magmatic eruptions in 1980 (May 18, May 25, June 12, July 22, August 7 and October 17, 1980).This magma produced the distinctive plinian, explosive eruptions for which the volcano is famous.That concept began with eighteenth-century French naturalist Georges Cuvier, picked up steam with Charles Lyell, and it has been in vogue ever since.This is despite the fact that it causes more problems for interpreting rock strata than it solves.His result was in close agreement with his estimate of the age of the earth.The solar estimate was based on the idea that the energy supply for the solar radioactive flux is gravitational contraction.