Is pulverized rock, lava fragments, and ash erupted from a volcano.

Pyroclastic material is pulverized rock, lava fragments, and ash erupted from a volcano. There are four types of pyroclastic materials namely volcanic bombs, lapilli, volcanic ash, and volcanic blocks. They are commonly associated with Plinian or Krakatoan eruption styles and the phreatomagmatic eruptions.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.

Increasing the release of greenhouse gases and pollution