of rocks of Precambrian age and overlying oldest sedimentary sequence of late Proterozoic to Eocene age. Its geological significance led to it being declared a National Geological Monument. The igneous cycle has three phases namely, the volcanic, plutonic and hypabyssal. The eruption is reported to be of fissure type. The pyroclastic exposed in a thickness of to is followed by rhyolite flows of to thickness. Sandstones of Jodhpur Group form the basal part of the Marwar Supergroup and the upper boundary of these volcanics is considerably eroded. The two formations called the Sonia Formation (sandstones) and the Girbhakar Formation (sandstones) occur unconformably over the eroded surface of Malani Volcanic rocks at the top, which comprise the Pokhran Boulder Bed (developed locally around Pokhran) with the Jodhpur Group as the basal part. The sandstones are creamy (reddish maroon upwards), and widely used as building stones. Further classification of the Malani Igneous Suite has been done by Bhushan (1991) as Granite Plutons (at least 15 varieties including the Jodhpur Rhyolites), the Siwana Granites (several plutons covering an area of within the Malani Igneous Suite) and the Jalore Granite (covers an area of including of Sankara pluton). Geological age The geological age of the Malani Igneous Suite assessed by several geologists vary. Crawford and Compston (1970) assessed the age by Rb-Sr classification as 745 ± 10 Ma. They also reported, in 1975, that the Isochron age was 735 Ma which was less than the age of 840 Ma for Sandra Granite, 830 Ma for Erinpara Granites and 820 Ma for the Pali Granites. But the Geological Survey of India in its publication National Geological Monuments (2001) has given the age as 600±70 Ma. Geodynamic significance of Malani Magmatism The 732 million years old anorogenic, A-type magmatism of North-Western Indian shield is characterized by volcano plutonic ring structures and owes its origin to mantle plume. This magmatism has great geodynamic significance in the configuration of the Malani Supercontinent comprising trans-Aravalli block of North-Western Indian shield, Arabian-Nubian shield sessions, Madagascar, South China, Tarim, Mongolia and Siberia. Legend The lone human occupant of the hill before the Mehrangarh Fort was built, was an old hermit named Cheeria Nathji, the Lord of the Birds. The hill and now the fort is habitat to thousands of birds, particularly the Cheel or Kite, the sacred bird of the Rathores. When Maharana Jodha wanted to build a fort on top