Pyroclastic material is ejected from a volcano during an explosive eruption. These fragments are defined by their size, which ranges from less than 2 mm to greater than 64 mm.

Ashis less than 2 mm in diameter, with an appearance of dust or sand.
Lapilli, or cinders, range from 2 mm to 64 mm in diameter. These pyroclasts are commonly pea to walnut sized. Blocksand bombsrepresent the largest fragments, which are greater than 64 mm.
Blocksare erupted as hardened lava with a mostly angular shape, while bombsaresemi-molten and develop a streamlined-shape while flying through the air. HelpReset

As this less than 2 mm in diameter, with an appearance of dust or sand. These pyroclasts are commonly pea to walnut sized.Lapilli, or cinders, range from 2 mm to 64 mm in diameter. Blocks And bombs represent the largest fragments, which are greater than 64 mm. Blocks are erupted as hardened lava with a mostly angular shape, while bombs semi-molten and develop a streamlined-shape while flying through the air.

Explanation:

A pyroclastic material is a particle ranges for the 2 to 64 mm in diameters and they can range of the volcanic bombs to the ash and the lavas.Like Lapilli or the cinders, they have a diameter of about 64 mm. They extend to miles form the volcano when they blast as blocks and can devastate lands, life, and property within there paths.

I'm pretty sure it's c. extremely gradual but not 100% sure though.