The geological history of the Earth covers billions of years! In Geological History, students will examine a time line of the Earth, tracking its violent beginnings and ever-changing face. Discover the four major segments of geologic time (the Precambrian and the Paleozoic, Mesozoic and Cenozoic eras), and learn about the plant and animal life that developed during each. A journey under the sea shows how geologists study the layers of rock that lie deep under the ocean floor, while a fun, hands-on investigation demonstrates how geologists can "read" unusual formations in rock layers. This title includes a teacher's guide.