Final answer:
Mount St. Helens in Washington and Paricutin in Mexico are both stratovolcanoes that have experienced significant eruptions, altering their landscapes and providing valuable scientific insight.
Step-by-step explanation:
Mount St. Helens and Paricutin are similar in that they are both stratovolcanoes which have had significant historical eruptions. Mount St. Helens is located in the state of Washington, USA, specifically in the Pacific Northwest region. It spectacularly erupted on May 18, 1980, with the eruption causing a massive landslide, significantly altering the landscape and releasing large amounts of carbon-containing gases. Paricutin is a volcano in the state of Michoacán in Mexico and emerged suddenly in a farmer's cornfield in 1943, providing scientists with an unparalleled opportunity to study the birth, activity, and life cycle of a volcano over the nine-year period that it was actively erupting.