Simplify the following text for a Grade 9 native English-speaking person.
Original: A pyroclastic flow ( also known as a pyroclastic density current ) is a common result of volcanic eruptions .
Simplified: These pyroclastic flows glowed red in the dark . Pyroclastic flows that contain a much higher proportion of gas to rock are known as `` fully dilute pyroclastic density currents '' or pyroclastic surges .