This essential volume explores the slow but mighty shifts that created the continents and that continue to shape modern landscapes. Readers will look at theories put forward through the ages to explain volcanoes and earthquakes, and they''ll examine how geologists learned what we now understand about Earth''s crust. In a world of constant movement, how do these ever-shifting plates affect our lives today? Photographs, diagrams, and sidebars help students understand the science that answers this and other questions.