The New Canaan Historical Society has extensive files that document houses, many of which are gone now, including by demolition, the head of the organization said Thursday. Curious people, such as descendants of those who used to live in those homes, often visit the Oenoke Ridge Road organization’s research library to find out what they can about them or to view photographs of the structures, according to Executive Director Nancy Geary. Yet in the case of a pre-American Revolutionary War era White Oak Shade Road home that’s undergone an unpermitted demolition of its second floor, that’s no longer possible. “From our point of view, for there not to be a process where we can at least get out and document what was there, what was the original 1750 house, to preserve that for the records of New Canaan history, to me is a great shame,” Geary said during a meeting of the Historical Review Committee. The volunteer group convened in the Historical Society’s Town House to decide whether to delay the demolition-in-progress at 251 White Oak Shade Road, a project that’s been under a cease-and-desist order from New Canaan’s chief building official since Feb.