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The Green Meridian — Part 3: Finding the monolith - Chuck Fisher's LiveJournal [entries|archive|friends|userinfo]
From Bay Area to Barcelona

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The Green Meridian — Part 3: Finding the monolith [ Tuesday, 18 Dec 07 | 14:10 ]
ursine1
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[My Location |El Masnou (Barcelona) España]
[My Mood |amusedamused]

Armed with my Garmin GPSmap 60C handheld navigator and knowing that the Green Meridian’s longitude of 2° 20′ 14.025″, I figured the monolith would be easy to locate. The flyer from the Ajuntament said that it was located along the passeig Marítim at the mouth of the Teià River. How could I miss?

I started the walk on the sea-side walkway that runs from Badalona to Mataró. As I strolled closer to the monolith, I kept my eye glued on the Garmin’s display. Being out in the open, there was a clear view of probably 10 GPS satellites which provided an estimated position accuracy of 3 m (10 feet).

With the map zoomed very close, my position on the display changed every few seconds. Finally I reached what the GPS device said was the correct longitude. But there was no monolith to be seen.

I took a closer look at the longitude and discovered that it was in the format of hddd° mm′ ss.sss″ but my Garmin was set to display hddd° mm.mmmm′. So after changing the data format, I had to retrace my path a couple hundred meters (yards) until I was again supposedly at the correct longitude.

At least now I could see the mouth of Teià River. I looked around and then I saw it, monolith and all.

Monolith commemorating the Green Meridian
You can see the granite marker on the ground leading to the monolith.

But still I wondered, how could my GPS be off by so many meters when the accuracy was supposed to be 3 m? The answer was that I was using the map datum of WGS 84, which is used in the US, but Europe uses a different datum. When I changed the datum, the monolith was within the reported GPS accuracy.

Granite line marking the Green Meridian

I noticed that crossing the paseo was a granite line marking the Green Meridian. How could have I missed it? By paying to much attention to the GPS display and not looking around for obvious landmarks. At least my embarrassment was kept to myself.

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