Answer:
SHIELD VOLCANOES
Explanation:
Shield volcanoes are composed almost entirely of relatively thin lava flows built up over a central vent.
Most shields were formed by low viscosity basaltic magma that flows easily down slope away form the summit vent.
The low viscosity of the magma allows the lava to travel down slope on a gentle slope, but as it cools and its viscosity increases, its thickness builds up on the lower slopes giving a somewhat steeper lower slope.
Most shield volcanoes have a roughly circular or oval shape in map view.
Very little pyroclastic material is found within a shield volcano, except near the eruptive vents, where small amounts of pyroclastic material accumulate as a result of fire fountaining events.
Shield volcanoes thus form by relatively non-explosive eruptions of low viscosity basaltic magma
