Final answer:
The statement that ocean ridges and volcanic islands are formed at divergent plate boundaries is true. Such formations occur as molten rock from the mantle rises up to fill the gap between tectonic plates, creating new oceanic crust and sometimes volcanic islands.
Step-by-step explanation:
True: Ocean ridges and volcanic islands are indeed formed at divergent plate boundaries. Ocean ridges, such as the Mid-Atlantic Ridge, occur when tectonic plates pull apart and molten rock rises to fill the space, solidifying to form new oceanic crust. This process typically takes place beneath the oceans, leading to the formation of long chains of underwater mountains known as mid-ocean ridges. Volcanic islands can also form in divergent boundary zones, often as a result of volcanic activity associated with the thinning of the Earth's crust and the upwelling of magma.
Most divergent plate boundaries are located in ocean basins, with molten basaltic lava from the mantle rising up to form the igneous rock of the ocean floors. Sometimes, these divergent boundaries can be found on land, such as the East African Rift. Mid-ocean ridges are frequently offset by transform faults due to varying rates of seafloor spreading along their length, which can create a zigzag pattern.
Through the creation of new crust at rift zones and volcanic activity at subduction zones, important processes of the Earth's plate tectonics become evident, allowing us to understand the dynamic nature of our planet's surface. Ultimately, the activity at divergent boundaries contributes to the continuous remodelling of the Earth's surface, including the formation of oceanic lithosphere and volcanic islands.