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
The Public and its Problems what he saw as argumentation on the part of Lippman that was particularly doctrinaire and absolutist in its judgements, and saw his own philosophical pragmatism as a means by which a more accurate and realistic conception of what the public and democracy was capable of it, and its limitations. Dewey begins his argument by distinguishing between the "state," represented by elected lawmakers, and the "public," the diffuse, often incoherent body of citizens who elect the state. The public is called into being when ordinary citizens experience the negative externalities (or consequences) of exchanges beyond their control (such as market or