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GoGaslightYerself t1_j4q30ec wrote

Municipal engineers still use the old maps of NYC to locate water-main breaks, etc., since an underground water-main break in one location will often follow old stream beds and then come up above-ground somewhere else...this helps them locate the broken pipe by following the old stream bed back uphill/upstream...

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ClamatoDiver t1_j4q820c wrote

A few years back there was major signal work done on the Dyre Ave line north of E180th.

There was a constant flow of water in some sections that was only found after digging and they couldn't locate the source.

I had seen some old maps before because I liked looking up the history of the area, I happen to live in that section. I did more searches and found one that had old streams and sure enough there were several that used to cut across where the tracks are now.

Old streams don't go away when you build up the land, they just flow deeper.

This isn't the same map, but this shows the streams north of the R in Westchester

Bronx 1891

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GoGaslightYerself t1_j4q8hdg wrote

I also always heard that the skyline of NYC echoed the bedrock below -- with tall buildings built where the bedrock was near the surface, and shorter buildings built where the bedrock was deeper and harder to access without caissons -- but more recently I've read that this is a myth that is largely untrue...

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ClamatoDiver t1_j4qcc97 wrote

I'm unaware of that, but I've been fortunate enough to have touched the bare bedrock that was there before the section of the Second Ave line north of 63rd and Lex was finished.

That's listed as 155 ft deep.

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GoGaslightYerself t1_j4qrqzh wrote

Lots of old history on the island. It's wild to imagine there once being farmland on Manhattan!

https://www.businessinsider.com/manhattan-nyc-farmland-photos-2017-6?op=1

So much has changed...my grandfather had his office in Manhattan, and my Dad said that when he was a kid, he used to take his 22 rifle with him on city buses to get from his home in north Jersey to a shooting range in Manhattan, and he said nobody really batted an eye ... can you imagine that happening today?

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