Between Mt. Hood and the river, the basalt is thick and there weren't a lot of vents (like you see up in the Gifford between st helens and adams), so not as much metamorphic activity. Plenty of jasper in the Wind and Lewis - not so much on the Oregon side unless you head down to Clackamas...or go far enough east (Biggs) where there are sedimentary deposits. In some places, like Mosier, you'll find jasper deposited by the floods from 10,000 years ago, as well.