Magma and lava are the same substance in two different forms. Magma is molten rock that is found beneath the earth's crust, while lava is what magma becomes once it reaches the surface and erupts from a volcano or crack in the earth.Know More
Magma can also contain many other components besides just molten rock, including gases and crystals. This mixture maintains a temperature between 1,600 and 2,400 degrees Fahrenheit. The molten rock often contains silicon, iron, carbon, aluminum, magnesium and different alkalis. Magma is heated by geothermal convection and pressure. Typically, it is found several kilometers beneath the earth's surface.
The composition of lava determines whether its flow is explosive, fast-moving or slow and highly viscous. Temperature plays a less significant role in the look and feel of the volcanic rock that forms once the lava cools down. Pumice is one igneous volcanic rock that is shaped by its composition and the type of eruption. As lava violently shoots into the atmosphere, it rapidly cools and decompresses, allowing air bubbles to permeate the rock, leaving a bubble-marked texture and a light weight. Obsidian, on the other hand, is a high-silica rock that forms from quick-cooling lava found on the ground in highly viscous flows.Learn more about Volcanoes
Volcanoes occur when magma from the earth's mantle reaches the surface. This can happen at the place where two tectonic plates diverge or converge. It can also occur in a place called a hotspot, in which magma from the mantle reaches the surface in the middle of a tectonic plate.Full Answer >
Mount Shasta's magma is composed of basalts and basaltic andesite. These two types of magma are very runny, forming large shield cones and steep, loose tephra cones. The basaltic andesites at Mount Shasta are unusually rich in magnesium.Full Answer >
Volcanoes occur when magma is able to reach the surface of the Earth through a gap in the crust. This typically occurs at plate boundaries, where two tectonic plates pull away or move against each other. Volcanoes can also form at weak points in plates, called hot spots.Full Answer >
A volcanic neck, also called a lava neck or volcanic plug, is a cylindrical-shaped volcanic landform created when magma hardens inside the vent of a volcano, according to the University of Wisconsin. Examples of volcanic necks include Devil's Tower in Wyoming, Lizard Head in Colorado and Morro Rock in California.Full Answer >