Science Help.?

Ok. In science, we are learning about minerals. I need some ideas on how 3 Igneous rocks, like Obsidian, pomis(sp), or schale, and an Sedimentary rock, like Sandstone, could all come together in any wyoming area. We have to make volcanos into the story, of course since Volcanoe's are one of the ways an Igneous rock forms. SO I need to tell how they could all join together in ONE spot in an wyoming area. And I don't live in wyoming. I've heard about Vedawoo, and I was thinking of saying that it used to be a volcano, and the eruption was mive, turning everything to lava, and as they cooled all rocks were formed and found in that area. Sorry if its confusing. Put it this way...I need to figure out how all four rocks could be found in an wyoming area, involving volcanoe's, and the story can be fake. Thanks all!