I thought the same thing, until I looked at a map. Broadly speaking, rocks east of Orcas, including Lopez, are the same as Mt Erie. Mt Constitution is composed of very different rocks, which could be many tens of millions of years older, and generated thousnads of miles away from the Erie rocks.
I have climbed on what Billygoat is talking about and it is indeed the same stuff as Erie. Not talking about Mt. Consitiution, which is a heap of choss in comparison (not saying that Erie and Lopez climbing is that great.....but)