Explain why large fields of felsic lava flows are rare

What makes some lavas more fluid than others?

How is the explosivity of a volcano related to its magma chemistry?

How does the chemistry & gas content of magma determine the shape of a volcano?

Felsic lava is highly viscous, it consists of a polymer structure. Therefore it does not flow too much. Hotter felsic lava, however, can flow longer.