Hot dry rock geothermal energy makes use of hot fluids found naturally in basement rock; but such HWR conditions are rare. By far the bulk of the world’s geothermal resource base (over 98%) is in the form of basement rock that is hot but dry—with no naturally available water. This means that HDR technology is applicable almost everywhere on earth (hence the claim that HDR geothermal energy is ubiquitous). Typically, the temperature in those vast regions of the accessible crystalline basement rock increases with depth. This geothermal gradient, which is the principal HDR resource variable, ranges from less than 20 °C/km to over 60 °C/km,
Hot Rocks 1964–1971 Hot Rocks 1964–1971 Hot Rocks 1964–1971 is a compilation album by the Rolling Stones released by London Records in December 1971. It became the Rolling Stones' best-selling release of their career and an enduring and popular retrospective. While the album carries most of the band's biggest hits during their first decade, it does drop a few of them to include standout album tracks such as "Play With Fire", "Under My Thumb" and "Gimme Shelter" giving listeners a more well-rounded impression of the Rolling Stones' music in this era. "Hot Rocks 1964–1971" peaked at No. 4 on the Billboard 200 album