Hidden New York: The 1811 street plan

A year or so ago my son and I were watching a History Channel show on how researchers had 1811 Steet Gridreconstructed the original topography of Manhattan, before developers flattened most of the hills south of 96th Street. One segment focused on a couple of geographers who used GPS to find original markers from the Commissioners' Plan of 1811, which laid out the dreary grid that defines the island north of 14th Street.  The markers - iron bolts sunk into the ground at each planned street intersection - would have been uprooted where streets were built, but might still survive in Central Park. I went to look at a marker they found, couldn't find it, and ended up contacting Reuben Rose-Redwood, who teaches geography at Texas A&M and was featured in the History Channel show. Reuben couldn't have been kinder; he answered:

"As for finding the iron bolt, I actually sometimes get lost looking for the bolt myself! So, my best advice is to look on GoogleMaps for the intersection of what would have been 65th Street and Sixth Avenue."

After a bit of climbing around the rocks just off the 66th Street Transverse, I snapped this picture with my cell phone. The bolt is sunk deeply into the Manhattan schist, which is the only reason it survived almost 200 years.

Where there's one marker, could there be more? Probably not. After all, I had a hard time finding it even when I knew where it was. The professionals know exactly where the markers should be, and this is the only one they've found. Says Reuben: 188 survey bolt

"We've already looked through Central Park and Marcus Garvey with GPS and Randel's survey notes in hand. Based on his field notes, we know where all of the bolts should be. We've gone to all the locations and can't seem to find any others (which may be underground or destroyed)."

But there's hope. What about Morningside Park or an eastern sliver of Riverside Park? It looks like the original grid included parts of both of them. If anyone has a GPS unit and wants to go looking for more bolts, leave a message in the comments.