The volcano type is very broad and large in diameter, with very gently sloping sides. it must have formed from viscosity lava (which is also low is silica).

The shield volcano type es very broad and large in diameter, with gently sloping sides. It must have formed from low viscosity lava (which is also low in silica)

Explanation:

The viscosity of lava depends on different factors, like water, mineral crystals, bubbles and silica content. The silica content is one of the most important factors, because it has a characteristic chemical link between Si and O that can make a flow behave like something between liquid and solid, being more viscous when there is a high amount of silica.

Low vicosity lava flows very easily, almost like water, and for that reason, when a volcano send down this kind of lava, it flows around, reaching larges distances before cooling down and forming a rock, thereby, the structure of the volcano is longer than high and with very gently sloping sides.