Jawaharlal Nehru Technological University Hyderabad B.Tech II GENERAL GEOLOGY Previous Question Paper (May/June - 2019 - R16)

The mantle is the thick, middle layer of the Earth located between the crust and the core, extending to a depth of approximately 2,900 km. It is primarily composed of silicate rocks rich in magnesium and iron, existing in a solid state that exhibits plastic or ductile behavior over geological timescales, which facilitates mantle convection and plate tectonics.

Continental drift is the hypothesis that Earth's continents have moved over geological time relative to each other, appearing to have "drifted" across the ocean bed. Proposed by Alfred Wegener in 1912, the theory suggests that all present-day continents were once joined together in a single supercontinent called Pangaea.

The theory is supported by several lines of evidence, including the jigsaw-like fit of continental coastlines (such as South America and Africa), the matching of fossil records across widely separated landmasses, and the correlation of distinct geological structures and mountain belts on different continents. While initially controversial due to the lack of a known mechanism, it laid the foundation for the modern theory of plate tectonics.