National Geodetic Survey Benchmarks

This is a Feature Layer used by the NGS - GPS on Bench Marks Web Map.This feature layer has all of the First and Second order National Geodetic Survey Bench Marks.  This data set was created by extracting all of the NGS Datasheet shape files that had a VERT_ORDER of 1 or 2.  This feature layer is symbolized based on the combination of 3 attributes.  Descriptions for these attributes is below.Distance - A bench mark that is greater than 30 km from a bench mark used to create GEOID12/12A/12B [GEOID12B GPS on BM are purple diamonds on the map].Scaled - A bench mark that has a SCALED position source.  This means this bench marks position was determined by surveyors using a USGS Topographical Quad Map.Last Recovered - A bench mark where no mark recovery has been submitted to NGS in over 30 years.The symbology was created to allow the symbols to stack if all 3 attributes -- or any combination of the 3 -- are present.