Proto-Metal

Proto-metal (also known as heavy rock, and heavy metal) was a genre of rock music that developed in the early 1970s, largely in England and the United States. Bands such as Black Sabbath and Deep Purple, pioneered the sound of metal, by developing a riff heavy sound, characterized by amplified distortion, guitar solos, emphatic beats, and overall loudness. Oftentimes nowadays these bands aren't considered fully metal with the exception of Black Sabbath.

Characteristics
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History
To be added.

List of bands
Black Sabbath (Birmingham, England)

Deep Purple (Hertford, England) (Deep Purple In Rock, some songs after)

Led Zeppelin (London, England) (some songs)

Budgie (Caerdydd, Wales)

Sir Lord Baltimore (Brooklyn, New York)

Blue Öyster Cult (Stony Brook, New York) (some songs)

Queen (London, England) (some songs on their early albums)

Judas Priest (West Bromwich, England) (first album)