Sometime during the 1906, the United States Coast and Geodetic Survey (USCGS) now National Oceanic and Atmospheric Administration (NOAA), established a geodetic marker drilled in a cubic meter of diorite rock on a mountaintop located at the boundaries of Brgy. Argao, Hinanggayon and Silangan, Mogpog, 13°33'41"N, 121°52'3"E. This is the Luzon Datum of 1911, a very important geodetic point marker which is used as point number one for all map makers in the country. This marker is at first level accuracy.