On June 30, 1934 Edith A. Harrison, RD, Ancram, NY submitted an application to the State Education Department for a historical marker to be placed at the Jansen Kill.  The annotated schematic map indicated that the marker was erected on the south side of Ancram-Pine Plains Road, approximately one mile east of that road and another road identified as "P. Plains Rd."  The marker seems to have disappeared but was still there in September-October 1954, according to an inventory of markers made at that time. 

A Legend Gives A Community Its Name
James Polk  History of the Roeliff Jansen Area, 1990

The Story of Roeliff Jansen
Margaret Hunt, former Historian, Town of Hillsdale
from "Remembrances of Things Past"
Roe Jan Independent, February 21, 1974}

Roeliff Jansen
Margarita Dearlove
Unpublished paper for local history class 
at the Roe-Jan School, 1962