BY TIM WOGAN
The Earth’s crust hasn’t changed much over the past 3.5 billion years, say researchers who have analysed the ratio of two titanium isotopes in ancient shales. Their findings suggest that plate tectonics started much earlier than most previous models suggest.
Geologists divide Earth’s crust into two broad classes of rock. Mafic rock, which makes up the ocean floor, is dense, dark and rich in minerals such as magnesium and iron. Continents comprise felsic rocks such as granite, which are lighter and richer in silicon and aluminium.
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https://www.chemistryworld.com/news/titanium-analysis-puts-new-date-on-earths-continental-crust-/3008034.article
