igneous age The period of time since a rock, such as some types of meteorite, solidified and crystallized from a molten state. This can be derived from the ratios of the radioactive elements of certain elements, such as samarium-neodymium (Sm-Nd) and rubidium-strontium (Rb-Sr). Related category GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |