rocks which are intruded in many places by granites of Ordovician (c. 500 Ma) and early Miocene (c. 22 Ma) age. Although most of the metasediments forming the HHCS are of late Proterozoic to early Cambrian age, much younger metasediments can also be found in several areas, e.g. Mesozoic in the Tandi syncline of Nepal and Warwan Valley of Kistwar in Kashmir, Permian in the "Tschuldo slice", Ordovician to Carboniferous in the "Sarchu area" on Leh-Manali Highway. It is now generally accepted that the metasediments of the HHCS represent the metamorphic equivalents of the sedimentary series forming the base of the overlying "Tethys Himalaya". The HHCS forms a major nappe which is thrust over the Lesser Himalaya along the "Main Central Thrust" (MCT). Tethys Himalaya (TH) The Tethys Himalaya is an approximately 100-km-wide synclinorium formed by strongly folded and imbricated, weakly metamorphosed sedimentary series. Several nappes, termed the "North Himalayan Nappes", have also been described within this unit. An almost complete stratigraphic record ranging from the Upper Proterozoic to the Eocene is preserved within the sediments of the TH. Stratigraphic analysis of these sediments yields important indications on the geological history of the northern continental margin of the Indian sub-continent from its Gondwanian evolution to its continental collision with Eurasia. The transition between the generally low-grade sediments of the "Tethys Himalaya" and the underlying low- to high-grade rocks of the "High Himalayan Crystalline Sequence" is usually progressive. But in many places along the Himalayan belt, this transition zone is marked by a major structure, the "Central Himalayan Detachment System", also known as the "South Tibetan Detachment System" or "North Himalayan Normal Fault", which has indicators of both extension and compression. See ongoing geologic studies section below. Nyimaling-Tso Morari Metamorphic Dome (NTMD) "Nyimaling-Tso Morari Metamorphic Dome" in the Ladakh region, the "Tethys Himalaya synclinorium" passes gradually to the north in a large dome of greenschist to eclogitic metamorphic rocks. As with the HHCS, these metamorphic rocks represent the metamorphic equivalent of the sediments forming the base of the Tethys Himalaya. The "Precambrian Phe Formation" is also here intruded by several Ordovician (c. 480 Ma) granites. Lamayuru and Markha Units (LMU) The Lamayuru and Markha Units are formed by flyschs and olistholiths deposited in a turbiditic environment, on the northern part of the Indian continental slope and in the adjoining Neotethys basin. The age of these sediments ranges from Late Permian to