Rock is a form of popular music that emerged in the 1950s and that by the end of the 20th century was the world’s dominant form of popular music. It originated in the United States and spread …

Nov 25, 2025 · Rock, in geology, naturally occurring and coherent aggregate of one or more minerals. Such aggregates constitute the basic unit of which the solid Earth is composed and …

Nov 6, 2025 · Sedimentary rock, rock formed at or near Earth’s surface by the accumulation and lithification of sediment or by the precipitation from solution at normal surface temperatures.

Nov 8, 2025 · The confrontation in Little Rock drew international attention to racism and civil rights in the United States as well as to the battle between federal and state power.

Dec 2, 2025 · Alternative rock, pop music style, built on distorted guitars and rooted in generational discontent, that dominated and changed rock between 1991 and 1996. It burst …

Rock history can thus be organized around both the sound of cities (Philadelphia and Detroit, New York City and San Francisco, Liverpool and Manchester) and the spread of youth cults (rock …

Rock art includes pictographs (drawings or paintings), petroglyphs (carvings or inscriptions), engravings (incised motifs), petroforms (rocks laid out in patterns), and geoglyphs (ground …

Nov 25, 2025 · Lava, magma (molten rock) emerging as a liquid onto Earth’s surface. The term ‘lava’ is also used for the solidified rock formed by the cooling of a molten lava flow.

Rock Island, city, seat (1833) of Rock Island county, northwestern Illinois, U.S. It lies on the Mississippi River (bridged to Iowa) at the mouth of the Rock River and opposite the island for …

Nov 21, 2025 · Rock and roll, style of popular music that originated in the United States in the mid-1950s and that evolved by the mid-1960s into the more encompassing international style …