Surprising evidence of Ordovician rocks in the oldest part of the Lesser Himalayas

Some Ordovician trace fossils from the Nigali Dhar Valley: a) Phycodes; b-d) Palaeophycus; e) Diplichnites

A conclusion on the presence of Ordovician rocks was expressed by the group of Indian geologists co-operating with ichnologist Radek Mikuláš of the Institute of Geology, Czech Academy of Sciences. The Lesser Himalaya mountain belt has been as yet considered to be built from Proterozoic and earliest Palaeozoic (Cambrian) rocks. However, newly collected rich assemblages of trace fossils (i.e., traces after activity of invertebrate organisms) contained in certain portions of the tectonically isolated block of the Nigali Dhar Valley contain trace fossils from the so-called Cruziana rugosa Group, which are considered typically Ordovician in age. They have been reported from epeiric seas of the former Gondwana Supercontinent. The finds, therefore, represent evidence of prolongation of the Ordovician Gondwana sea to the Indian continental tectonic plate.