Structure of the Earth obducted onto the continental crust and preserved as ophiolite sequences. Many rocks now making up Earth's crust formed less than 100 million (1) years ago; however, the oldest known mineral grains are about 4.4 billion (4.4) years old, indicating that Earth has had a solid crust for at least 4.4 billion years. Earth's mantle extends to a depth of 2,890 km, making it the thickest layer of Earth. The mantle is divided into upper and lower mantle. The upper and lower mantle are separated by the transition zone. The lowest part of the mantle next to the core-mantle boundary is
What We Do Elation" (1995). All tracks written by John Scofield. What We Do What We Do is the second studio album by jazz group The John Scofield Quartet. It was recorded in May 1992 and released the following year on the Blue Note label. Besides John Scofield on guitar, the quartet features saxophonist Joe Lovano, Bill Stewart on drums and Dennis Irwin on bass, replacing Marc Johnson. Irwin and Scofield (both born in 1951) had already recorded together in the mid-1980s with Bennie Wallace on a track for his album "Sweeping Through the City." Irwin would be the bassist on two more