Plate Tectonics From Hypothesis to Theory Plate tectonics is a scientific theory that explains two centuries of often puzzling observations and hypotheses a bout our planet Earth. a The continents are drifting very slowl across the face of our planet Continental drift is a concept with a long history
Introduction: What Is an Igneous rock? Igneous rocks vary greatly. Some contain large mineral grains. Others contain grains so small they can barely be seen under a high power microscope. Igneous rocks also vary greatly in color. All igneous rocks are formed through the cooling and solidification of magma
Introduction: Weathering The Breakdown of Rock At the Earth's surface, rocks are exposed to the effects of weathering: the chemical alteration and mechanical breakdown of rock, when exposed to air, moisture, and organic matter. Weathering is an integral part of the rock cycle. Weathering converts rock to regolith
Introduction: Sediments In The Rock Cycle Sediments are transported by: Water. ce Wind. Gravity. The transport and deposition of sediments are initial phases of the rock cycle. The ultimate fate of most sediment is burial and conversion to sedimentary rock
Introduction: Earth's' Internal-- Thermal Engine Magma is molten rock beneath Earth's surface. Because liquid magma is less dense than surrounding solid rock, and obviously more mobile, magma, once formed, rises toward the surface. Magma that reaches the surface does so by erupting through vents we call volcanoes
Earth's Internal Structure When a meteorite impacts a planet or moon, its energy of motion (called kinetic energy)is transformed into heat energy. As Earth grew larger and larger from continual impacts, its temperature increased. Radioactive decay of materials like uranium, thorium and potassium also added heat
