World Climate and Climate Change | Class 11 Geography Notes

Minor Relief Features

In addition to the major divisions of the ocean floor, several minor but significant relief features exist. Mid-oceanic ridges are underwater mountain ranges composed of two parallel chains separated by a central rift valley. These ridges can have peaks rising as high as 2,500 meters, with some parts like Iceland emerging above sea level. Seamounts are isolated underwater mountains with pointed summits that do not reach the ocean surface; they are volcanic in origin and can be 3,000 to 4,500 meters tall. Guyots are flat-topped seamounts that have subsided over time, becoming submerged flat-topped mountains. Submarine canyons are deep valleys cutting across continental shelves and slopes, often extending from large river mouths; the Hudson Canyon is a notable example. Atolls are ring-shaped coral islands surrounding a lagoon, typically found in tropical oceans. These minor features contribute to the ocean's complex topography and influence marine ecosystems and oceanic processes.

📊 Diagram: Figure 12.2: Relief features of ocean floors

🧪 Activity: Identify mid-oceanic ridges and seamounts on ocean floor maps; discuss their formation.

🔗 Connection: After understanding ocean floor topography, the chapter proceeds to study ocean water temperature and its distribution.

Table on page 3 (2×2)

| Water storage in oceans | Evaporation

Table on page 3 (2×2)