1.   Anaxagoras planned to demand some solid data on the volcanic activity which kept shaking Mount Aetna.

2.   In this case, it is the formation of the rock through volcanic activity, which drives off any argon formerly present.

3.   Scientists took readings over several weeks and found that there was no unusual volcanic activity.

4.   Solids can release gases back into the atmosphere when heated and pressed by volcanic activity.

5.   The plates realigned and subduction resumed, sparking volcanic activity which spewed forth the granite rock covering much of the Sierras.