From the tallest mountains, all the way to the deepest ocean trenches, plate tectonics explains all the features & movements of earther’s surfaces in both the past & present.
Plate tectonics, the theory that earth’s external shell is separated into numerous plates which glide over the rocky internal layer of the core called the mantle. The plates act like a rigid & hard shell compared to earth’s mantle. The lithosphere is what the strong outer layer is referred to as.
Developed between the 1950s all the way through to the 1970s, plate tectonics is the up-to-date version of the theory first proposed in 1912 by the scientist Alfred Wegener, called continental drift. Alfred Wegener couldn’t explain how the continents move around the plant but …show more content…
• They are low, with mildly sloping sides.
• They are form because of eruptions of runny, thin lava.
• Eruptions are usually regular but relatively mild.
Composite volcanoes • Made up of alternating layers of ash & lava (other volcanoes consist of just lava).
• They’re typically located at destructive boundaries.
• The eruptions from these volcanoes tend to be a pyroclastic flow (a mixture of hot steam, ash, rock & dust.) rather than a lava flow.
• A pyroclastic flow can roll down the sides of a volcano at extremely high speeds & with temperatures higher than 400°C.

Volcanic eruptions can have overwhelming effects on the environment & people
Although, unlike earthquakes, volcanoes can also have a positive impact on an area.
Positive + & negative - effects of an eruption
Positive + Negative -
Extra income could be brought to an area, because tourists are attracted to the dramatic scenery created by volcanic eruptions. Volcanic eruptions usually lead to many lives being lost.
Valuable nutrients may be provided to the soil when lava and ash (from the eruption) are deposited and breakdown. This is good for agriculture as the soil becomes very fertile. Lahars which are fast moving mudflows that are created when ash and mud from a volcano eruption mix with rain water or melting