A. B. Roy, MSc, 1961; PhD, 1965 (Jadavpur University) is a Retired Professor of Geology at M.L. Sukhadia University. He was a Fellow of the Alexander von Humboldt Foundation for post-doctoral work at Rurh University in 1975-76. He was elected Fellow of the Indian Science Academy, Bangalore, in 1989, and the Indian National Science Academy, New Delhi, in 1990. He has published two books, a number of edited volumes, and over 120 research papers and scientific reviews on different aspects of Earth science.Ritesh Purohit, MSc (1995); PhD (2002) (ML Sukhadia University) is an Associate Professor in Geology at the Government College, Sirohi, Rajasthan, India. He has been engaged in teaching and research for the last 22 years and has more than 100 research publications to his credit. He is involved in many international research collaborations including the Carnegie Institution of Washington, USA. He is a recipient of post-doctoral research awards from UGC and DST of the Govt. of India, and grants from NASA, International Atomic Energy Agency, Geological Society of America, International Geological Congress and UNESCO-IGCP for research activities.