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 (ITS utility) What (ITS utility) What (typed as in the prompt) was a small information utility available in the Incompatible Timesharing System. It could provide information about incoming email, bus schedule on the MIT campus, executable source files or answer the user in a humorous manner. was written in the MIDAS assembly language. It can still be used on some of the ITS instances maintained across the web. The last traceable edit of the source code was by Ken L. Harrenstien on 16 May 1988. Without arguments would print information about inbox status: With the argument bus it would print out information