Death by volcano?

The discovery of anomalously high levels of mercury in rocks from the Ordivician geological period has led to a new interpretation of the ensuing mass extinction. A sequence of disturbances may have led to catastrophic cooling by reflective sulfate aerosols injected into the atmosphere by massive volcanism. The finding is important since aerosol cooling is under consideration as a way to temper global warming.
Geology News — ScienceDaily