Could a series of eruptions possibly have caused the extinction of the dinosaurs due to the ash depoited in the atmosphere?

Lots of people have definitely proposed that idea, but it is still not decided. For one thing there would have to be eruptions such as we've never seen before. About the only possibility would be a flood basalt eruption (and one did indeed occur around the 65 million years-ago time). The only problem is that flood basalt eruptions aren't explosive. They are persistent though so they might have filled the atmosphere with enough sulfuric acid aerosols (vog) to make life difficult. There's no doubt that a big meteorite hit around 65 million years also. One idea I've heard lately is that the flood basalt eruption (the Deccan Traps in NW India) had stressed life on the planet, and the big meteorite impact was the last straw.

There have been other global extinctions, and if you go by the percentage of Earth's life that has disappeared in them, the one 65 million years ago is not the most drastic. What I wrote above would require that a meteorite hits during a time of flood basalt volcanism more than once. Is that too much of a coincidence to occur multiple times? I don't know.

Scott Rowland