The Ordovician rocks of Mount Everest

The highest rocks on Earth, marking the summit of Mount Everest, are Ordovician limestones, deposited in a warm, shallow-water sea some 450 million years ago. More remarkably, these rocks still contain the fossils of marine animals such as brachiopods, conodonts and crinoids that occupied tropical habitats during one of the most important intervals in Earth history, the Great Ordovician Biodiversification Event (GOBE). These rocks, deposited in an ancient Tethyan Ocean were thrust and uplifted into their present commanding position when Indian collided with the Asian continent some 55 million years ago.

Strata at lower altitudes, equivalent to those of the summit of Everest, have yielded new shallow-water faunas dominated by brachiopods and crinoids (Harper et al., 2011) The shallow-water shelly faunas were dominated by suspension feeders including orthide and strophomenide brachiopods (Zhan et al., 2014), and a robust pentameride crinoid, ‘Pentagonopentagonalis’ (col.) sp. (Donovan et al., 2012). New conodont data precisely correlate part of the succession with the P. serra conodont Zone (upper Darriwilian); the Colour Alteration Index of the conodonts indicate a finite temperature of 350OC to 5500C (Stouge et al., 2021). This fauna was part of the Toquima-Table Head Realm, a circum-equatorial province during the late Middle Ordovician.