An important step in scientific petrography

Abstract

(Regarding Bowen's book The later stages of the evolution of the igneous rocks). The author of this note has long distinguished between normal igneous rocks with more or less strict signs of chemical equilibrium and anomalous ones, not amenable to any laws of equilibrium and any strict scientific classification, but bearing bright signs of the sequential course of the phenomenon, which, thanks to them, can be clarified in its sequence. Such rocks can only be described, and historical and geological dates can be deduced from the inventories. Now, after the publication of Bowen’s important work, one is involuntarily inclined to think about a very weak representation of normal breeds and, perhaps, even their absence; In nature, only approximations to them are presented, which is why we have to look at them not as normal, but as ideal.