a style of rock primarily focused on rhythmic repetition, commonly with a psychedelic bent and often featuring extended track lengths, which emerged out of the post-punk movement in the late 1970s. minimal rock was heavily informed by the postmoderist classical movement of minimalism and following movements like glenn branca's totalism, and it commonly overlaps with the neo-krautrock revival of 1970s german krautrock in its use of a steady motorik rhythm.
closely related to minimal rock, this style tends to have a reduced rhythmic presence in favour of emphasis on texture, particularly incorporating electronic instrumentation and more atmospheric guitar work akin to the studio-based 1970s art rock of brian eno, as well as the psychedelic tape-effects of dub reggae. ambient rock developed in the 1980s alongside ambient pop, a genre even further removed from its rock roots, though the two styles share plenty of overlap. this style was particularly associated in the early 1990s with the lost generation movement in the uk, and has been dubbed the "too pure sound" due to many of its prominent acts appearing on that label.
this style, commonly nicknamed "crescendocore", is a later development which focuses on dynamic progressions and changes over time, drawing on the structures of 1970s progressive rock and commonly incorporating chamber or orchestral instrumentation to build up to grand crescendos. crescendo rock emerged in the 1990s and rose to popularity in the early 2000s, notably being associated with explosions in the sky.
although broader than post-rock, this late 1980s kentucky indie rock scene included prominent early post-rock groups slint and bastro who adapted the abrasive sounds of post-hardcore and noise rock into more complex and dynamic arrangements which helped to establish the genres of slowcore and math rock. following both groups' breakups, a second wave of the scene with a more folk and americana based sound emerged in the 1990s, including gastr del sol and rachel's.
closely related to the louisville sound, this scene features a more prominent influence from jazz, particulary jazz fusion. the most well-known group in the chicago school is tortoise, but it also encompasses john mcentire's other group the sea and cake, isotope 217, and some 1990s works by experimental musician jim o'rourke.