What geological feature is created when magma squeezes across rock layers and cools?

The correct answer is a dyke, which is formed when magma intrudes into existing rock layers and solidifies. Dykes typically cut across the layering of the surrounding rock, allowing them to be distinguished from other geological features. This process involves magma rising through cracks or fissures in the Earth's crust, and as it hardens, it creates a vertical or near-vertical sheet of igneous rock.

Understanding the formation of a dyke is crucial as it illustrates the dynamic processes of the Earth’s geology, specifically how magma interacts with existing formations. Sills, although similar, are formed when magma intrudes parallel to the rock layers rather than perpendicular, which distinguishes them from dykes. A lava flow refers to the movement of molten rock on the surface, which does not involve the creation of intrusive features like dykes or sills. Lastly, a fault line involves a fracture in the Earth's crust where two blocks of rock have moved relative to each other, which is a different geological phenomenon from the intrusion of magma.