Himalayan Geology, Vol. 21 (1& 2), 2000, pp. 87-97, Printed in India

Faunal and Floral Diversity in the Subathu-Dagshai Passage Beds: a Review

S.B. BHATIA
House No.441, Sector 6, Panchkula 134 109, India

The Subathu Formation was deposited in a shallow marine, tidally influenced peri-sutural basin between the initial and terminal India-Eurasia collision. The nature of the contact between the Subathu Formation (Early Iierdian to Early Middle Lutetian) and the overlying Dagshai Formation (Late Eocene-Oligocene) representing a fluvial/flood plain arid setting has been the subject matter of controversy for more than three decades. The controversy centers round the transitional or passage beds (sensu Bhatia and Mathur, 1965) comprising mainly purple and variegated siltstones/shales with calcareous nodules and at palces with oyster bands and or bone beds between the youngest Nummulities-bearing olivegreen shales and the overlying distinctive white/green quartzitic sandstone forming the base of the Dagshai/Murree Formation. Some workers place the passage beds at the top of the Subathu Formation, while others include them in the Dagshai Formation.

In recent years the passage beds have yielded a wealth of terrestrial and aquatic vertebrates, marine and non-marine mollusks, ostracodes, smaller foraminifera, charophytes and palynofossils. The passage beds, because of their distinctive lithology and stratigraphic position, are easily correlatable in different localities of the Lesser Himalaya. This paper discusses the faunal and floral diversity, the age implications and broad depositional environments of the passage beds of selected localities.