Yes study materials are important for gate exam because there is a huge competition for doing m.tech in IITs.

Graduate Aptitude Test in Engineering(GATE) is a national level exam to test the performance and understanding capability of students in their graduate fields. This test is useful for the admissions in M.E/M-Tech and other NITs Through out the India. GATE exam is jointly conducted by the seven IITs(Indian Institute of Technology) and IISc(Indian Institute of Science) on behalf of the  National Coordination Board – GATE, Department of Higher Education, Ministry of Human Resource Development (MHRD), Government of India. 

Few useful books are:

• Advanced Engineering Mathematics – Erwin Kreyszig
• Engineering Mathematics solved papers – Made easy publications.

• Objective English for Competitive Examination 5th Ed – Hari Mohan Prasad.

Engineering Geology-R. Nagarajan, A. Parthasarathy, V. Panchapakesan

Principals of Engineering Geology-K M Bangar

Fundamentals of Geophysics-William Lowrie