A horizontal intrusion of molten magma into the bedding plane of sedimentary rocks is called

The correct answer is a sill. When molten magma intrudes into the bedding plane of sedimentary rocks, it can form a horizontal sheet-like body called a sill. The magma solidifies and becomes a new layer of rock that is parallel to the existing sedimentary layers. Sills are usually less than a few hundred meters thick and can vary in size from a few meters to several kilometers in length and width. Sills are commonly found in areas of volcanic activity and are an important feature in the study of geology.