‘What type of plate boundary is shown in this illustration? A) mantle boundary B) transform boundary C) divergent boundary D) convergent boundary ‘
The Correct Answer and Explanation is:
B) transform boundary
This illustration depicts a transform plate boundary, which is characterized by two tectonic plates sliding horizontally past one another. The prominent blue arrows in the image, which trace the general path of California’s San Andreas Fault system, clearly show this sideways or shearing motion. This specific boundary separates the Pacific Plate on the west from the North American Plate on the east.
At a transform boundary, the lithosphere is neither created nor destroyed, which distinguishes it from the other two major types of plate boundaries. In contrast, at divergent boundaries, plates pull apart, creating new crust as magma rises from the mantle. At convergent boundaries, plates collide, resulting in the destruction of crust through subduction or the formation of large mountain ranges.
The immense friction between the two massive plates at a transform boundary prevents them from sliding smoothly. Instead, stress builds up along the fault line over many years. When the accumulated stress finally overcomes the friction, the rock fractures and slips, releasing a tremendous amount of energy in the form of an earthquake. The San Andreas Fault is famous for generating frequent and sometimes powerful earthquakes that shape the landscape and pose a significant hazard to the region.
The topography shown in the image, including the linear arrangement of valleys and the offset of geological features, is a direct result of this long-term horizontal movement. Over millions of years, the northwestward movement of the Pacific Plate relative to the North American Plate has sliced through the crust, creating the distinct geological features that define the California coastline and interior ranges.
