Not exposed on the surface but Ape Cave near Mt. St. Helens is basalt: https://wa100.dnr.wa.gov/south-cascades/ape-cave

"Ape Cave formed about 2,000 years ago, when an 8-mile-long lava flow known as the Cave Basalt poured down the southern flank of Mount St. Helens. As it flowed, parts of the lava started to cool, forming a hardened crust and creating an insulated tube for the still-molten lava flowing inside. Scientists estimate that the lava in the Ape Cave tube continued moving for as much as a year. Eventually, the last of the molten lava drained out through the hardened tube, leaving the interior empty. Over time, sections of the hollow tube collapsed from above, creating several natural skylights. The largest of these collapsed sections now forms the entrance to the cave."

Nick Zentner on Ape Cave: https://www.youtube.com/watch?v=Uks7Fq67YOk

If there are others like me who are discovering an interest in geology (in my case well after my school years), Nick Zentner has a few different series on YouTube.

The I-90 Rocks series he did and posted under the hugefloods name was a great entry point for me. Highly recommend for some easy to consume videos about familiar areas.

If you like them, he goes deeper on other channels.