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 Call of Earth had a weak connection, and so delay the eventual time when the Oversoul loses control of the people of Harmony. The characters listed here are those whose primary role is in "The Call of Earth." For other characters, see Homecoming Saga. The Call of Earth The Call of Earth (1992) is a science fiction novel by American writer Orson Scott Card. It the second book of the Homecoming Saga, a fictionalization of the first few hundred years recorded in the Book of Mormon. The book focuses on several key events that happen after Nafai, Elemak, Issib, Mebbekew, Zdorab and the