Here's how interactions in the Earth system could have led to dinosaur extinction. About 65 million years ago, a huge asteroid hit Earth in part of what is now Mexico. The asteroid blasted a deep crater in the spot where it landed, and it also caused changes to other parts of Earth's geosphere. Volcanic eruptions began to increase. Lava-molten rock from deep underground-poured out of volcanoes. The lava covered hundreds of miles. Is the lava what killed off T. rex? No. The lava covered a huge area, but it was small compared to the entire surface of Earth. Hot lava did not kill every T. rex on earth. The explanation is more complicated than that.