What is sheild and composite volcano

A shield volcano has shield-like shape. They are typically very large in area but their cones have a smoother, lower profile than composite volcanoes. They are shaped this way because their lava flows are made of basaltic magma, which has a lower viscosity than the lava from composite volcanoes. This characteristic allows the lava to flow much farther from the caldera and in thinner layers. Mount Kilauea, Hawaii is a well known shield volcano. It has been erupting continuously for over thirty years.

Composite volcanoes are more commonly called stratovolcanoes. They are the stereotypical volcanoes that come to most people's minds when they think of volcanoes. They can be quite steep. They are called composite because their cones are built of layers of tephra, ash, pumice and lava. This is also why they are called stratovolcanoes--another word for “layers” is “strata”. The lava from the volcanoes is felsic and has a high viscosity, so they slow and cool more quickly than the lava flows from shield volcanoes.