OK, turning to my geologic dictionary, Dacite has a bit less silica than rhyolite...but a lot more than basalt. In order of less to more silica, volcanic rocks go: basalt, andesite, rhyolite. The dictionary says dacite has a composition like andesite, except more silica....
One thing I was curious about is whether any of the cascades volcanoes are capable of having a lava flow of basalt, which would flow faster.....like Etna or on Hawaii......I guess it would have to come out of a new magma chamber, or with an injection of new magma from the mantle..... There were massive lava flows of, I think, basalt in the northwest about 15 million years ago...Columbia flood basalts (??)
Chris