Tortoise's 1994 debut album was the start of an underground musical revolution in American indie rock. While a few British bands had already begun playing what would come to be known as "post-rock," Chicago's Tortoise planted the flag in America and became the linchpins for a voluminous, vital wave of post-rockers. Tortoise simultaneously poses and answers the question "Can you still be a rock band if you renounce (for the most part) the use of vocals and guitars?" The band further complicate—or simplify, depending on your viewpoint—the question by bringing in all manner of non-rock influences, from funk grooves and dub reggae production techniques to jazz fusion sensibilities and ambient textures. Most of the tracks on the band's debut are led by the rhythm section, with bass and drums generally establishing a sinuous groove over which such traditionally non-rock instruments as vibes and melodica are laid. The resulting a feel is at once propulsive and atmospheric. But from the visceral nature of the grooves to the no-frills production, Tortoise bears plenty of rock attitude.