jacquesh2001
I found only one Schartt (see first ref below) circa 1889 - a John schartt but there is no trace that he ever painted. On the other hand, I wonder if you did not misread the signature (sometimes they are difficult to read) and if the name is not Schwartz. In which case there is -was- a Barbara Schwartz who died in the late 70's, and a Gerald Schwartz, still alive but he says he painted mainly landscapes since 40 years, that could be your man.

sunshine_today
search on name plus subject of painting/medium of painting, see if you can get any hits from that.