GEOLOGY

Detailed explanation-1: -Many rift valleys are part of “triple junctions, ” a type of divergent boundary where three tectonic plates meet at about 120° angles. Two arms of the triple junction can split to form an entire ocean.

Detailed explanation-2: -Divergent plate boundaries, which are associated with the formation of rift valleys, occur when plates move away from one another. Convergent plate boundaries move toward one another, pushing into one another and are likely to create mountain ranges.

Detailed explanation-3: -A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth’s mantle to the surface, solidifying to create new oceanic crust. The Mid-Atlantic Ridge is an example of divergent plate boundaries.

Detailed explanation-4: -Areas where plates are colliding form convergent boundaries, and areas where plates are expanding create divergent boundaries. Rift valleys are formed by divergent boundaries that involve continental plates.

Detailed explanation-5: -Most divergent boundaries are located along mid-ocean oceanic ridges (although some are on land). The mid-ocean ridge system is a giant undersea mountain range, and is the largest geological feature on Earth; at 65, 000 km long and about 1000 km wide, it covers 23% of Earth’s surface (Figure 4.5. 1).