Hi Caroline. Welcome aboard.
You're correct about the dating of the marbles. Turn of the century (with maybe some from the 1800's) into the 1950's.
Plus one probably from the 1960's and one group I can't place at all -- might have thought modern if they were standing alone but since they're in such an old group, I'll be very interested in seeing more views of them. (Those are the black and oranges which come up as lot #2 for me.)
Those stone aggies have seen some marble battles!
A very nice inheritance.
One group per thread in the ID forum would be the way to go for us to give you more specifics about your treasures.