The Geological Survey of India (GSI), established in 1851, is one of the oldest geological organisations in the world and operates under the Ministry of Mines. Junior Geologists conduct systematic geological mapping, mineral resource surveys (coal, iron ore, rare earth elements, uranium), groundwater studies, and natural hazard assessments (earthquakes, landslides, glacial lake outburst floods). They work in field surveys across all terrains from Himalayan glaciers to coastal sedimentary basins, contributing critical data to India's mineral exploration and disaster management agencies.

GSI Junior Geologists are recruited through the UPSC Combined Geo-Scientist Examination. The exam has two stages: Stage I (Preliminary CBT with 100 MCQs in 120 minutes covering Geology, Physical Geography, and Mathematics) and Stage II (Descriptive papers—Geology Papers I, II, and III—each of 3-hour duration). Shortlisted candidates appear for a personality test (interview) conducted by UPSC. The overall selection process is rigorous and tests both theoretical depth and field geology understanding.

The Geology section covers Physical Geology, Geomorphology, Mineralogy, Petrology (igneous, sedimentary, metamorphic rocks), Structural Geology, Stratigraphy, Palaeontology, Economic Geology (mineral deposits), Applied Geology, and Remote Sensing. Physical Geography includes earth's interior, plate tectonics, geophysical methods, and oceanography. The Mathematics section tests basic statistics, numerical methods, and data interpretation relevant to geoscientific analysis. Candidates should consult the official UPSC Geo-Scientist syllabus for the full and updated topic list.

GSI Junior Geologists are placed in the Central Government pay scale at Group A Level 10 (approximately Rs. 56,100–1,77,500 per month) with additional field allowances for remote postings. GSI officers frequently work in remote field locations—Himalayas, Northeast India, Andaman Islands, and Peninsular India. Accommodation in field camps, geological survey vehicles, and project-specific allowances are provided. Career progression leads to Senior Geologist, Director, and Director General of GSI. GSI also offers postings in international bilateral survey missions.

Study standard M.Sc. Geology textbooks across all core branches: Blatt et al. for sedimentary petrology, Best for igneous petrology, Yardley for metamorphic petrology, Davis and Reynolds for structural geology, and Singh for economic geology. Solve UPSC Geo-Scientist previous year papers extensively—these provide the best understanding of exam depth and expected answer quality. Practise map reading, cross-section drawing, and geological log interpretation for the Stage II descriptive papers. Physical Geography and basic statistics can be covered from UPSC Geography optional books.