Final answer:
The claim that Mt. St. Helens' eruption was bigger than Yellowstone's is false; Yellowstone's eruption was much larger and had a greater impact.
Step-by-step explanation:
The statement that Mt. St. Helens' eruption in 1980 was much bigger than Yellowstone's eruption 640,000 years ago is False.
The eruption of Mt. St. Helens in 1980 was indeed a catastrophic event that caused significant alterations to the landscape, including the destruction of forests, the formation of a massive debris avalanche, and the release of large amounts of carbon-containing gases into the atmosphere. However, the size and impact of the Yellowstone eruption, which occurred 640,000 years ago, were far greater. That eruption formed the Yellowstone Caldera, a volcanic feature approximately 34 miles by 45 miles in size, and was one of the largest volcanic events known in the last 2.5 million years.