What are tectonic plates floating on

Introduction to convergent plate boundaries

A convergent plate boundary is a place where two tectonic plates move towards each other, often causing one plate to slide under the other (in a process known as subduction). The collision of tectonic plates can lead to earthquakes, volcanoes, mountain formation, and other geological events.

Key Findings: Convergent Plate Boundaries

• When two tectonic plates move towards each other and collide, they form a convergent plate boundary.

• There are three types of convergent plate boundaries: ocean-ocean boundaries, ocean-continental boundaries, and continental-continental boundaries. Each is unique due to the density of the panels involved.

• Convergent plate boundaries are often sites of earthquakes, volcanoes, and other significant geological activity.

The earth's surface consists of two types of lithospheric plates: continental and oceanic. The crust that makes up the continental plates is thicker, yet less dense than the oceanic crust because of the lighter rocks and minerals that make it up. Oceanic plates are made up of heavier ones

Basalt, the result of magma flowing from mid-ocean ridges.

When plates converge, they do so in one of three settings: ocean plates collide with one another (form ocean-oceanic boundaries), oceanic plates collide with continental plates (form ocean-continental boundaries), or continental plates collide with one another (form continental-continental boundaries).

Earthquakes are common whenever large plates of the earth come into contact, and convergent boundaries are no exception. In fact, most of the Earth's strongest tremors have occurred at or near these limits.

The earth's surface is made up of nine large tectonic plates, ten small plates, and a much larger number of microplates. These plates float on the viscous asthenosphere, the upper layer of the earth's mantle. Due to thermal changes in the mantle, tectonic plates are always moving - through the fastest moving plate, the Nazca, only move about 160 millimeters per year.

Where plates meet, they form different boundaries depending on the direction of movement. For example, transformation boundaries are created in which two plates rub against each other when they move in opposite directions. Different boundaries are formed where two plates pull apart (the most famous example is the Mid-Atlantic Ridge, where the North American and Eurasian plates diverge). Convergent boundaries are formed wherever two plates move towards each other. During the collision, the denser plate is typically peeled off, which means that it slides under one another.

When two oceanic plates collide, the denser plate sinks below the lighter plate, eventually forming dark, heavy basaltic volcanic islands.

The western half of the Pacific Ring of Fire is full of these volcanic island arcs, including the Aleutian, Japanese, Ryukyu, Filipino, Mariana, Solomon, and Tonga-Kermadec. The Caribbean and South Sandwich island arcs are located in the Atlantic Ocean while the Indonesian archipelago is a collection of volcanic arcs in the Indian Ocean.

When oceanic plates are peeled off, they often bend, resulting in the formation of oceanic trenches. These often run parallel to volcanic arches and extend deep below the surrounding terrain. The deepest oceanic trench, the Mariana Trench is more than 35,000 feet below sea level. It is the result of the movement of the Pacific Plate under the Mariana Plate.

When oceanic and continental plates collide, the oceanic plate is subducted and volcanic arcs form on land. These volcanoes release lava with chemical traces of the continental crust through which they rise. The Cascade Mountains in western North America and the Andes in western South America have such active volcanoes. Italy, Greece, Kamchatka and New Guinea too.

Oceanic plates are denser than continental plates, which means they have a higher subduction potential. They are constantly drawn into the mantle, where they are melted and recycled into new magma. The oldest oceanic plates are also the coldest as they are separated from heat sources such as diverging borders and hot spots. This makes them denser and more subtractive.

Continental-continental convergent boundaries press large plates of crust against one another. This results in very little subduction as most of the rock is too light to be carried very far into the dense mantle. Instead, the continental crust at these convergent boundaries is folded, flawed, and thickened, forming great mountain ranges of uplifted rock.

Magma cannot penetrate this thick crust; instead, it cools down obtrusively and forms granite. Highly metamorphic rock such as gneiss is also common.

The Himalayas and the Tibetan Plateau, the result of a 50 million year collision between the Indian and Eurasian plates, is the most spectacular manifestation of this type of border. The rugged peaks of the Himalayas are the highest in the world. Mount Everest reaches 29,029 feet and more than 35 other mountains exceed 25,000 feet. The Tibetan Plateau, which covers approximately 1,000 square miles of land north of the Himalayas, has an average elevation of 15,000 feet.