I'm trying to ID what I initially thought was a black walnut until I noticed the terminal leaflets and fruit... The tree is near Victoria BC. I wasn't able to get better pics of the leaf scars or bark, or a branch to examine the pith, but I may be able to return to the site to get them later.
Thanks - those were my thoughts too on the leaves. Apparently the two species hybridize quite readily so I imagine it could also be a bit of both...