During the 1896 field season, the surveying crews of the U. S. Geological Survey (USGS) engaged in higher quality and more precise topographic mapping and spirit leveling than had been previously attempted. This change was largely prompted by an act issued by the Fifty-Fourth Congress on June 11, 1896. For USGS, the most significant result […]
You are here: Home / Archives for Amerisurv Feature – The Early Vertical Datums of the U. S. Geological Survey