Famous Eruptions & Pangaea

You know an eruption can bury a town, as Vesuvius buried Pompeii. In 1980, Mount St Helens erupted in Washington State. A landslide removed its northern flank. The pressure drop triggered a sideways blast. In 2010, Iceland's Eyjafjallajokull sent ash over Europe. Flights stopped because ash can damage engines. To find years between two events, subtract the earlier year from the later year.

The landslide removed rock that had held pressure inside the volcano.

Wind can carry eruption ash and gases far from a volcano. Ash may darken skies and change weather for a short time. Most ash settles quickly. Lasting cooling mainly comes from sulfur dioxide gas forming tiny sulfate droplets in a high layer called the stratosphere. Winds spread these droplets. They reflect some sunlight back into space. With less sunlight warming Earth's surface, the global average temperature can fall for months or years. An average drop does not mean every place becomes cooler.

Sulfate droplets reflect some sunlight before it reaches Earth's surface.

Pangaea was a supercontinent, one vast landmass joining most continental land. It began breaking apart about 200 million years ago. Continents ride on tectonic plates, so their positions can change as the plates move. Their usual motion is only a few centimetres a year. Small changes add up over millions of years. Today's continents did not always sit in their current places.