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General Category => General Discussion => Topic started by: Tristar on April 28, 2012, 02:53:33 PM

Title: What does the 'BM' icon mean on a topo map?
Post by: Tristar on April 28, 2012, 02:53:33 PM
Garmin map 62S.   
I was scrolling a street map using NC topo map downloaded from here.  I found a round icon and when I hovered, it read  BM 1754.400 .   When I put the coordinates into a geocache benchmark search it goes to  benchmark FB3997.  The question is, is there a USGS page that would use the 'BM' number?  I've found nothing by 'googling'. 
Title: Re: What does the 'BM' icon mean on a topo map?
Post by: Indrid Cold on April 28, 2012, 07:15:35 PM
Quote from: Tristar on April 28, 2012, 02:53:33 PM
I found a round icon and when I hovered, it read  BM 1754.400 .   
When I put the coordinates into a geocache benchmark search it goes to  benchmark FB3997. 
You may have noticed the for FB3997 the Altitude is 1754.40
But to answer your question, it's not the USGS, but the NGS: http://www.ngs.noaa.gov/

This is also a source of shapefiles for those that want them.
Title: Re: What does the 'BM' icon mean on a topo map?
Post by: Tristar on April 28, 2012, 08:17:11 PM
I see that now, thanks.  It's easy to search the coordinates to get the number of the bm.   Thanks for clearing that up.
Title: Re: What does the 'BM' icon mean on a topo map?
Post by: Indrid Cold on April 28, 2012, 08:52:01 PM
Quote from: Tristar on April 28, 2012, 08:17:11 PM
I see that now, thanks.  It's easy to search the coordinates to get the number of the bm.   Thanks for clearing that up.
I think the mapmakers can use the source I provided to label with the PID, but the source they have been using they are labeling with the elevation.
Title: Re: What does the 'BM' icon mean on a topo map?
Post by: drzcharlie on May 09, 2012, 07:52:43 PM
Bench Mark
Title: Re: What does the 'BM' icon mean on a topo map?
Post by: Tristar on May 10, 2012, 04:28:08 AM
Finding no record of one I found the other day placed by the USGS, it's now registered with Waymarking.