Topo Symbol Help

been a while since I was up on the symbols but I believe they could be survey markers.




Senior Member
Somewhere that benchmark has a number as well as a northing easting on a plat


Senior Member
Fletch W, Like Quercus alba stated, those are Bench Marks. They indicate that the elevation was measured in a survey or for geological data. If a marker was placed on the spot, there would be a number on the map. Google up topo map bench marks for more.


Senior Member
USGS or CGS Triangulation Stations depending what year they were established, horizontal only, not vertical. Basically six miles apart maybe less. They were triangulated in at night using a wood or Bilby tower 60 to 100 foot high. Top of the tower was centered over the concrete marker and angles were turned to the center of the light.

Concrete markers are either 8" or 10" square and 4' long with a stamped brass disk on top. You would also have a identical marker underneath in case the top one got destroyed. Each one would have a azimuth marker as well, same type of monument but instead of the stamped triangle it will have a triangle with an arrow pointing toward the direction of the main station.

Elevations for these markers are generally within the nearest foot.