Intrusive volcanic landforms are collections of cooled magma that formed within the Earth's crust and were later exposed by surface erosion and uplift. The collective term for these land forms is pluton.Know More
Intrusions are classified as concordant or discordant. Concordant intrusions are parallel to the surface. Discordant intrusions are not parallel, and some are almost perpendicular. Batholiths, stocks and dikes are discordant intrusions, and sills, laccoliths and lopoliths are concordant intrusions.
Batholiths are massive discordant intrusions that have at least 100 square kilometers of exposed surface material and form deep within the crust. They are often comprised of multiple plutons containing various types of igneous rock. Stocks are discordant intrusions that are similar to batholiths except they have less than 100 square kilometers of surface exposure. Dikes are narrow, sheet-like discordant intrusions that formed as magma rose through vertical cracks in the crust.
Sills are concordant sheet-like intrusions that form between layers of sedimentary bedding surfaces. Laccoliths are mound-like concordant intrusions. They formed between layers of sediment and developed a dome shape as magma pressure from below pushed upwards into the rock above. Surface erosion can change a laccolith's shape. Devil's Tower in Wyoming is a well-known laccolith. Lopoliths are concordant intrusions similar to laccoliths, but their center has depressed to form a saucer shape.Learn more about Volcanoes
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 volcano forms when a vent in the Earth's crust allows magma to well up from below. The magma fills a void underneath the surface, and when it builds up enough pressure, it bursts through to the surface. As the magma cools, it hardens into rock, and multiple eruptions may build up the mountainous form of a volcano.Full Answer >
Volcanoes can form anywhere the Earth's crust allows magma to reach the surface. Typically, this occurs around plate boundaries, either where plates are pulling apart or where one is forcing its way under another. Weak spots can also develop away from plate edges, creating magma vents called hot spots.Full Answer >
Plate boundaries are the weakest points in the Earth's crust, which leads to cracks that allow magma to seep through and develop volcanoes, according to NEWTON. These areas are called "subduction zones." Subduction zones form the Ring of Fire, a volcanic region in the Pacific Ocean, explains Live Science.Full Answer >