Heavy rock is a genre of music that combines elements of hard rock and heavy METAL. It is characterized by aggressive guitar riffs, distorted vocals, and powerful drumming. The term 'heavy rock' can also refer to the physical objects associated with the genre, such as METAL and boulders. METAL is a type of solid material composed of a combination of elements, usually iron and other metals. Boulders are large rocks that have been naturally shaped by erosion or weathering. Heavy rock music and its associated physical objects are often used to create a sense of power and strength.