Victorian custom

[pompylen]

I've been trying to date a photograph and as there's no markings on the back it was suggested that I should study the ladies fashion and in particular the length of the dress worn, this way I would have an idea whether the person is a girl or woman. Could SKS tell me whether it was customary during 1870 to wear a full-length dress if the person was married? I know the rule was to lower the hem as she became older but what if she married young, would she still be expected to have her skirt to the floor?
Strange question but it would help me to know.

Len