EQT Study Guide Adv.

Scientists classify rocks by composition and texture. When igneous rock from magma cools slowly they have a coarse- grain. The landforms that we call volcanoes are created by repeated eruptions of lava. An active volcano is currently erupting or will erupt very soon. A combination of explosive and nonexplosive eruptions will create a composite volcano. A cinder cone volcano has steep slopes. When igneous rock from magma cools rapidly they have a fine- grain. Weathering forms sediment.

During a nonexplosive eruption you would see calm lava flows. Lava with a high viscosity is thick, like pudding. After an explosive eruption an area would experience darkened skies. Molten rock deep underground often gathers in a magma chamber. Surface waves cause the greatest damage in an earthquake. Primary seismic waves can travel through solids, liquids, and gases. Richter magnitude scale is used to measure the strength of an earthquake. The three main types of volcanoes are shield, composite, and cinder cone. The volcanoes of Hawaii and other places far from tectonic plate boundaries are known as hot spots.

An active volcano is most likely to erupt in the near future. An explosive volcanic eruption is the most destructive. Mount Rainier and Mount St. Helens are composite volcanoes. The strength of an earthquake is determined by the amount of ground motion. The epicenter of an earthquake is the point on Earth’s surface directly above the focus. Another word for an earthquake’s strength is its magnitude. The three types of plate motion are: divergent, convergent, and transform. Most earthquakes happen at the edges of tectonic plates. The area where two tectonic plates meet is called a boundary.

Wegener thought that all the continents were once together in one large continent called Pangaea. A possible result of plates moving along a transform boundary is earthquakes. When plates collide a convergent boundary is formed. When plates separate a divergent boundary is formed. When plates slide past each other a transform boundary is formed. According to the continental drift theory, a single, huge continent once existed called Pangaea. The core consists mainly of iron. The theory of continental drift explains why continents move. Earthquakes produce seismic waves.